TRANSHITTINGANTENNAS atrd GROUNDSYSTEHS for | 750 I,|ETERS

Edltedby Pllchael l"ltdeke

| 987 Reproducilonnights are reserved by the individual authors. Tableof Contents

Pop 5 TMNSNITTINGANTENMSFORI75O NETERS EdPhlllips TheLowrbrn, July'80 7 COUPLINOTHEVLF ANTENM TOTHE TMNSNITTER Phillips TheLsw6wn, August '80 IO ANOTHERUSTFOR POSTHOLTS flichellli&ke I I BASICI75Om TMNSI1ITTIN6ANTENM flitchellLee ItB Lowturn,August'86 I8 OPTINIZINOIHEPARTISANTINM '87 Hieke TfpLorbrn, April 20 NOTESON I 750I1ETER TRANSNITTINO ANTENMS/OROUNDS YincentPinto TheLowdorn, JEnuEry'84 2I TUNEDCOUNTERPOISE Kelth0lon WesternUpdate 445 2E NOTESONAD.JUSTINOI75OI1TTERTMNSNITTINOANTENMS Pinto TheLov6nn, may'84 34 IEOONTTER FITTD SIRENGTH NTASURENENTS RichordBrunrpr TheLowdown, July'83 39 LFSKYWAVESAND I750I1ETIR SKYWAVE ANTENMS lll&ke WesternUpcbte $36 4I SKYIXPERIMENTS Hl&ke 42 EFFECTSOFNOISTURE ONINSULATED AND NON-INSULATED OROUND MDIATS LesRayburn lheLmvdown, September'86 43 NOTEON OROUND I1OISTURE Niffie 43 FERRITELOADINO Nieke 44 SITEFACTORSAFFECTINGPERFORNANCEOF ITSOMTTER TPANSMITT I IS VERTICALS Ni&ke 45 TMNSNITTIIIGORCI.'NDS FORI75O I1ETERS Nideke 49 LOWPOWER ANTENM CURRENI AND POWER NETER DayeJohnston TheLo,{dorn,Norember'87 50 1750mRESISTA|{CE BRIDOI Lee WesternUpchte, Harch'86 52 RFANNETTR FOR 1750m IRANSIIITT|NOANTENMS Lee 54 LFDIPPER AND RESOMNCT CHECKER Johnston 56 I DOZENI750 T1EIER TMNfiITTINGANTENMS fli&ke WesternUo6te a9 57 LOI,IOWAVTXNTOAERIALS ArthurChlld December'82 58 TVERYTHINOYOUI1AY WANT TO KNOW ABOUT LITZ WIRE Kemign-LewisWire Profucts 59 FCCRULESANDRE0ULATTONS(P6rttS,abridged) 60 ART13 GOODIES Hi&ke 60 FERRITEHATCHINGTRANSFORI1ERS mkbke 2

I NTRODUCTI ON

This co! loction of articlos on l75O ms!e. transDittrnE antennaE, EroundE and nelated topica inclqdes mogt of what has appeared on tho subject in THE LOWDOWN since 1980. Other oatcrial has bcen drasn from th€ 1750 METER WESTERN UPDATE. I have added a scction on ground syst€ms to fill some minor geps in the existing material. Additional notes and illustrationg aro bainB addad on a spaca-avei,Iable basis as the cutting and pasting procaeds.

In assembl ing this col lcction I'v6 induLged my own incl ination ta brorge and coaparc, and thc reault is gaoewhet redundent. Anyone trshing to put up an effcctivo antenna can refer tq any of thc thrcr besia articlee (Phillips, Pinto or Lee) and leern what he needs to kno[. Although cmphesis varies, thc authors al I Elart fron thc saEc genenal prcmises and arri.va at the game gen€ral conc I us i onE .

But if you are looki.ng fon ideas or saaking, thc most practical soluti,on to gome particulan probleo, it will be vell rorthwhilc to study alI of the authors. Evcn if none of thom addnass your iDDediato eoncarn, it Dey bc that thcir combin€d ideas rill suggcst an answ6r.

For thc Dost part these articlag deal rith one basic antsnna typ6: the vcrtical radiator yith inductivc bese loadin6 and caPecitivc top loading. Whil.e therc are thasc rho 6ruoblc about incfficiency and maintain thet this is nat much of en ansrEcr !o tha problcms of radiating a signal at LF, thcse entennas hav6 at - lea€t two important thingE Eloing for thco thcy wonk and, if constructcd to the appropri,atc di,acnsiang, thay are accOptabls to th. FCC.

It Day wcl I bc that thcr6 arc Dorc afficicnt trangDitting ant6nnag for lhc purpose snd it ney bc that guch ant.nnas can be const.uctcd rithin thc diD6nEional congtraints of Part 15. Thus fer I've not gaen what I considar to be a proven degi.gn. K€ith OIson (7FS) has been doing i.ntersgting pork with l/lO gcale helical antenneg on 160 mctars.

Thc gcalcd dorn approach has a lot of o6rit. Onc can fi.nd out rhatha. thc deeign warks bgforc canfronting the di.fficultics of actual ly iDplcDcntinB it on longwavo. Thcec difficulties are fsr fron insignificant; 15 Dotcrs iE very snell in termg of our ravclan8ths but it is a big hunk of spac€ in the backyard. !'{cchsnical, alcctrical and edjustment difficultics abound! t hopc th€ following pa8eE will halp ta sDooth the way.

Hichacl Mideke- Novcmber 1987 TRAI{SI,IITTI116 ANTENT{AS FOR ]./50 I'IETERS sv Eo Pltut-tpsl'l6lZJ

As oenlioned in lhe introduclion (Vo1. 7 ,1 p B), suc- cessfuL tresmission rQulres tha! Lhe tran$lltirl8 &lenna be of @xinm possible height-, anC losses in f,he e!e@ ed g.M'l systes 5e as lox as possj.ble, I shall. nou describe sft EeieaaL properties of s@ll VLF ant.elms dd theia 8rcmd sysls, anJ Sive ex- dples of lhal yo @y ue! tr build. The 3nLema sysLm liLI flrsi be ccnsiJered frs a csslruc!iocl poin! of view, and lhe eleclrl.ai prlFrties wiII be discussed in their relatlon lc lhe ccupling sysiem desj€n ed construcaion, l-he paa&elers of lhe m!en- m as a circuit el.@n! HriI E 8iv6 nex!, foli@ed by the desi8n &d construalron of lhe circuits for c@plin8 the antenna !d tare tfras,rlter, !o8e!her wilh n,ethcxlsfor Lnerr ri-jstrent.

In practj.ce lhe desiSn of y@r an!e@ syst@ Ey t€

dictated by the space ya have available, 4 i9 !rue very ahort ete@ the mdiatim resishce is prc- in Dy m @. If yor space is li[ited detL give porti@] to the squres of the effective heighL ed up, brt ! rt up llE tallest thiry yo @, d fd aEy of the frequ@y. For & ul€ded &te@ 50 fet fM tre ed bJiIdiJEg G ya co, &d ltH 8i.ve li high the th@retical radiatim resist4€ at 1?5 Kltz a lry. ta Ey be pl€stly sprisedl is 6Iy 0.0312 otlEt thj.s is mly a very tiny frac- ti6 of lhe nldlM total resistece vlth rhich the There are rc Eygteries to rcrkirg at 175 KHz, since ate@ 9y9ts @ be buiIt, &d stws tbe itporiace u* of this lrequency Bes back !o the very ryl.i.est of keeping the losaes 6 Id a posibl.e. As & ex- 'rwirelesgr'. days of In fact, &y tood gld rirele$ eDle ol what this reare. il lhe etem cuMt is book lEs a realth of useful inforelion @ &iems 0.2 Mperes, a lypical value for a one MLt tmnsit- ad grods. The advice is excellent bul ha|{ !o Ler ed fairfy ld loss &te@ sysls (sw of 8rud fo1l.d. A. P. f,rorga's "uireless Telegraph Costruc- ed loading coil resislance eqEI lo 25 ofuE)' the ti@ For ArBteurs" (1911) devotes chapier 3 to "aer- €diated poHer !ill, be mly about 1/800 mtt, ed the iaLs ed ath cmecti6sr'. A feu quotes are of effj.ciscy uill be only 1/8 pe.cent! i.nterest: For a straight verilcal radrator rhose ]ength is a "In filting up a wj.rel.ess station the l@lion &d sll fraclion of a wavelength {the Evel.eigth of a erectio of e aetial. are of prire isporhcer &d 175 KHz sj.gEl is 5020,4 feet) the ste@ current the successful aeception &d laesission of cireless decreses linearly to zero at lhe @p. If €pacl- ressages Hj.1l depend 148ely upon its coditi@." hce is added at the loo, lhe cur.ent Lbere !s u- creased. If the currenl at the top is eq€l to lhe "The hj,gher e aerial is placed above the surface of curdt at lhe base Ine Ediation resishce tsill be the ryth, lhe rider uill be i.!s electrcstatic fieLd, f@r tiDes lM! of s u 1€ded eteM. For tbe ex- &d cmsequstly rcae pq{erful e}ectaic Eves Yill be eple given above lhis rculd ti€e e incese in ra- developed. Bdt after a height of 180-200 fet is diation resist&ce !o 1/8 ofu, of €diaied poerer to attalned, lhe engineeritg difficultj,es od the expen- 1/200 Ett (5 whole nilli€tts!), ed the efficiscy 9es ircEse I mpj.dly tl€t fd statifis exceed !t. @ld be 1/2 percent, Tbe effect,ive .{€e of the other thlngs being eqEl, lhe incr€sed ra€e in statio @td be doubled. N@ that I have discussed trryittj.r€ vaies 6 the sq€re of the bei"ght of the rerits of lop l,€dtng I rct point dt ihal rn the radj.atlr€ H1res. For exeple, a 25-f@t aerid. al1 prcbability y@ rrlL rct be able io use very och capable of L&$itting one nile ih@reti€lly sill of it. I lEve no idea hd lhe FCC 6r]d fel about snd Bves 16 nil€s if @de 100 feet h18h'n. atel@ installalions like those in the e@ples 3bove, partj.cularly if the height of Lhe vertical "After the linit i.n a verLical direcli.& has bes ecti@ is tbe @gic 15 ftters, but it is d@btful @hed, ihe 61y r@inin8 possibililies e to in- tbat tbey @ld be ve.y iBppy. If ve fudge the 15 cE* !h€ gwface ad spr€d out borizontally.n reters io 50 feet, which €s in the old rc€uLatihs before the FCC "renl metrlc'r, a liteml interpretation icprd (meti6s--the isporhce of a Sood atb eld ey tlEt a sing]e verti€l coductor 50 fet or grwnd c@ction cs hardly be oveaesti@ted ' 1on8 ls all tba! is ]egal, and if the Mlter elea c& lfhseve possible c@rciaL skti@s are lcted 6 !o d *gwnt I s sure that is rhat tbe rulin8 s]d @ist grud or n@ a body of cater so tfE! a tood be. (The best €y lo {in suah an rgwnt ls lo avoj.d grod Ey be secured by imbeddina zinc or copper i.t: keep your sigEls cl@ ed your at of band aa- plates in the @th or Eier . " diation to a minios ad you wiil not bring altentim to yourseLf. ) These quotatios re stlU pertj.nent loday' althdrgh Dote that !h€ q@tity wtrich vdies s the sqlre of Trc points .egardirg top l€ding @y b€ in order. tbe eteJ@ height ls the radialion resistsce, not Flrst, if He accepl the total length of the &teM to the electrlc fleld produced by tfF et@' 6 lbrgp be 50 feet, then there is rc advetaSe to reducing tlp irpUes rhs he $ys tbat lncBsiilS the h€i8ht by hei.ght of lhe ete@ ed t.1tring part of i! horizon- f@. tires irc@s the FnSe by 16 tl@s. H@ver, tally !o prcduce top 1€d1na. Il y@ @ get 50 fet becau$ of the incr€se jn ete@ systd efficj.ecy use lt. If rct, ti@ Eke th€ verti€]. *ctis as uith tbe ircrse in be!8ht' his t.@ks taLl. as y@ @ ild add top l€dint to brir€ the total rhich tcs "Ln ircI@1i8 ttE ra€e of the sbti6 e almst leJlAth to 50 fet, An shaped &te@ *111 b€ abort tTt corret. A fs lhings I did not quote e afs per- su€hlly betta than a shaped one in this €se, tinenl, especia.Lly his I.gfftwires as possible, ru out s far as possible. It tices ae sti]l necessary sd ae stj.ll foll.@d, 1n muld prcbably be 0K to ru ths over the edte of the spite of the ircree cost ssiated wilh th@, In @f ed dm to gMd leve1. 1 fEve e idea ttEt the case ol simple verti.al twrs the trwd syst@ such il installation niShl rcd( very tell, since it usuLl.y consists of "radialsn, or Hires mdj.aling rculd p.Lace the ete@ rell ai of the €y of rcs! fM the base of llF ateM in all direti@s to a !res, ed @ld a1s be convenient for lhe se of distue at l€st equl to the heiBhL of lhe t*r. tuy wj,res. The radial.s are usully buried beo€th the @lh with a speciaf p1or, in order to tet tb@ at of the my, As & eruple of e installation uhich viofates rcs! of the rufea 6ivs above, I xill. us my m alenna In prlnciple tbere is a cl€r distinction beireen ra- syst@ to she trtEt not to doil. The iorer is instal- diaL systs dd 8rod syst@. TtE pri@y purpose Ied in tlle mly spot my wife roId pemit, betren lhe of tbe radials i.s to eljeiEte lGs6 due lo cuMts ild the drlvffiy. One EU of w h@se rrnich e j,nduced in the aMd by lhe eletric field ls onLy trc feet aEy , ed extods up to the 30 f@L cf the dtffi, ed even fairly short radiaLs acc@p- @k. Trc larte €k trees gM Hithif, Ie$ tfan ten li.sh this. Htrever, there re stj.ll curHts fLrying fet of the tqer, ad nwros @lLia bshes are i,n the grod beyond the radial.s, 4d a conventl.ml, p]illed n€r the base, The $il, j,n N neithbortpgd grud is ofts oeeded in addillon to the md j.als. j.s sfB11ff, with lse gravel ad bqlld€rs udem€ttr, If the pll condrctivity !s p@r the Edials, togeth- ad the €ter table is at lest 100 fet dm. I have er Flih a fw t'ud rqb ad a cm@ti6 to the a fairly good grod cometion in lhe fm of a IM- Eter pipes, w1].1 prcbably be abqrt lhe best ttwd be.4 f,ire t.1ming to a recdtly installed copper E- that ce be fPped for. ler comectioo lo the stfeet, The pipe has a total Length of about 200 feet, but there@ no radlals &d E. A, laport gives il excell4t desdipli@ of grmd I have no space lo put th@. The Lotal resist&ce of systff 1n bis nRadig AnterE E€in€ring'r, llccmts dry antema systeo at present rs alrui 65 oi!E, a.I- HlI1, 1952, Sectlon 1,12 di$usses VLF grcud sys- !h@8h tshen I fj.rst j.nstalled the \,/LF 8€r ed had the is, Hh1le section 2,5 dscribes brud€st eteM €k trees pMed uay back I reasured strething iike Brud systeo design. The fatter secLion is of rcst 25 otes, ed ctu]d gei about 0,2e ilperes &tetuE cur- intqesl, since in it he glves data o the perfo@e rst lith one wall inpul !o the fie1. I believe that of a siDple verticaL radlator Hith Eri@s Is€ths in this inslallation t,he loss due !o lhe t.es is d@- ed nwbers of EdiaLs, The reslts @y be very i@t, although as a second faclor al] of Lhe surromd- crudely s@ized by syir€ that ECials cf length ing grcwd is very dry due lo bein6 under houses anl equal to the ete@ helght are a1rcst as g@d as drivesays. Cliff l.Jalker lBs a nuch simpler dte@ j.n rhose of infinite length, ild LfE! d len8rh of half rne niddl-e of his back yafd, wiih a mter pipe 8rcmd, the dtm height (atside di&reter of radial syst@ eo purr ou! a@uL tw-ce ai slrcn8 1 s-gnal as I oo. equal to ete@ hej,ght) is about 2/3 as effective as I th:nk the absence of the brg lrees is one @jor dif- very gEt len8th. Furthe@re, 2 radiais e abolt fepence. ed Lhe oresence of a watered Lam beneath half s 8aod 6 a very ldge nwber, ad 16 radia-ls the radirliI Ey be anolher. 5

llqr for re speciflc exalples of possible ateu ity, tut @ber that y@ dm't trt yu antffi io c@gtructio. In UE crutructio of the twble d(n, reking ilself &d everything ln the t@@1, qpfE- EdlatlrB setio i9 itldepddst gf rbetfEr top L€d- vtcinityl thtle re are @ this subJect I rust ina i.s used, e mst of the eEryles apply vllh or size the inportace of follwint the Bnufactuer's Flttst 1t, ftE sirpl€t aid 6rst etem tp ln- instructiG as io the size dd depth of the cecrete stall Ls a fe stsldirl8 *r of the type w€d to base ehlch is neded to kep ttle etem fM over- sppo.t TV &t@ ffiys e VHF/UHF tratslttlit ed lmjrt 1n the eind. Ity tmr tEs a base 3 feet Melvlnt 4tffi. TIF* mrs tqve the advatate qljft and 3 f*l dep, rbich is supposed to hoLd it of @cupyi.ng rinj@ nfl@r gpace" &d @ be pur- in a 75 dile t€r hor vind. Tfstrs a yatd of R€dy chased fM My @ufactwrs or distributors. This Hix, but srth it for the peace of mind it b.ings. to go 1f yd a affor{ ii, but the 19 a tood Ey I price is hlgh. As e exeple picked at randm fru a Hos! of yo prcbabl,y rcn I rMt lo 8o io the expsse j'nc@veni6ce recent j.ssue of IOFLDRAD10NEllS, Hil.l Radio' 2503 CE of a fre stadinS tqer' ed the of Rad, Bl(mington, lL 61701, offers a Rohn 48 f@t prcvidiig it Hith adequate base insulators ed tuys. prcbably fm a ilBxi free stedir€ ltrr lor $213,40. t@ @y be The best cmpmise ete@ is mde abl,e lo do a Lrttle better or a little rcrse by shop- 40 o. 50 f@t tel.escopint antem @st of the lype Radio plng rcwd l@alty, bu! this is the Seneral price c@nly used to support Fl4 ed Tv eten€s. E€e, Since the only Hind Loading @ Lhe toFer lill Shack lists a 36 f@l Gst for $42.95, ild the l€al be ilat of its M structw, yd shoul'd be abl.e io mdio stores ses to have slithtly taller ones for plenty get by uilh th€ very ]iSht6l Height of tmrs ad about a dollar a f6t. this &tema wiLf need sve re Mey t,fEt cay. For lhis expense you 6et of guy Hires, buL i9 reLatively €sy lo e€l ed bas e dle@ rhich @ be instaLled dythere yo ce ihe adviltage that almst no construction is required fd fee! of spacer ild'one that other tte Lo prcvide lt sith a Sood base insulator. flnd a sqll* 8]lwd j.n s11,1 rct involve a tangle of guy sires. If your ydd Since thj.s ireul.ator xiU be copresslon it cy be 1s s crsrded as oine Lhis @y be the 6Ly my you @de of t1as, ceruic, or 4y other 8@d insulating A beveEte bottle flill sene @ to. Eterial. l{ge 8L8s quite cet1, thorAh y@ have lo be cseful to oMt it The twr is a radiator (dteM), not m &leM I it cmot be broi(en by the sidMys mti6 of th€ ayst@. In addltlon lo tt€ suruding physical s- Est during instalLatid o. rhile beiiS blm by th€ "Hhere vlt@l rhlch Es disNed above in to in- wlnd, To be sure of el6tri€1. cotinulty, lhe sec- slall itn, the co|Pl,ete eteru syst@ includes ifE ti6s shold be el€trically cmecLed by slderir€ radlator, tlE base in$lator{s)' and the base itself' rirs b€!@ lhs {@y be diffi.cull' @st mst @t- ndesnri The latter trc c@porenis e rrth digcussinS. ln- e.ial like to slderrt) , or wing s1f taPpirg gul,atim of the etem i.s YetY iDportat' slnce $rfls ed 6berg to secure uire impers betr@ to s$tiss. The guys my be retallic, sd if s sh@ld losses in the insulator @ be a @ior cmtributo. 'e€8" ovemLl &tere loss, particulryly i, ret Heather. A be brcks every l0 feet or less rlih type polyethylse Ehut loss resistsce of a re8otD in parallel with stFin iEulators, Polyprcpylene 4d ys e!e@ @ Fri@sly reduce its effici@cy' In rcpe 1s q[ite ch€p, ed cill swe very reI1 lhs tfF €5e of a frc stodtnt t*r lhe base insulators drl|r. It has the advetaSe of oot r€qulring i@]a- Nt cTry tbe full @cbanical rind 1€d of the a- lors. tem, and tbeia cholce Nt be a c@ptlruse Fllen y@ electri€I perfo@ce ed strenglh. My oM ete@ If ya get a rct of Less ttEn 50 fel have @y yo us is a Hygain tfT-18 "Hi€h Toer" rhich oriticlly cffi choices of h@ lo we it, First of all, @ yo vtth rc kild of black "odu base iosulators. Hhen it as is, with s(m L6s in effici6cy. If dmrt nind taklng 1t dM later for isprcv@nls this @y I flrst tot @ WF I discovered itEt I cald nol l-€d ny stem at all {ho the base E tsetr or even wh@ be yw best chorce, since yd @ 6et on the air qtsd rith tbe €ther rc rci.st. I caldnrt m6w the thut se.. S€6d, ya @ it to S feet ltFre loss be@ it Es $ hi8h, hJt I @l'd guess it $ the 5 ild 10 f@t @st sectids nhich @ be had pretty 6y b do' Less ttEn 100K ot!s. I rc lucky @ou8h to flnd re ya get the @t. thls st@ld be its exlstin8 ltycalex isulators at a I@l saplus store r ed the thi.d, yo 6 bp 1€d i!, ej.iher at toP otere M i3 supported by nine of th@, €ch @e hei€ht or rith a c@biGt16 of extdslon @3t and FCC inch sqwe dd tF loches hith . SiDce Hycal,ex is 1€ahg. Thls i3 uhere the interpretalim ol the j 1€ve m Ey to fi€w very Bk in ieElon , I added a bolt , sblcb s insul-a- ru1e9 is fuzy, sirce lhey nls€tbn bp l@diry ddice is. For ted by e epory€lass bushint ' to €ch comer of the ,hat the of a egple, gppose yd l€d a 40 f@t t4r rith a 9]- bare to keep th€ insuLatoB sder cmpression rtlen "total bhe wind b1ds. Even this iEulati@ di€rades in ret id dlsk 10 f@i ln diffit*. Is the lettttlr" plus f€t, llE @lfFr, ed I regul4Ly cl@ the insulalors &d 40 f*t p16 10 f@t? Is it 40 fet 5 to the fathe@t 4- spEy th@ rith silicse oil Lubrl@t ' *rich belps @i@ dl8tee fM the base Eke tbe Eter inst€d of fomlng a fl1o trqity of the ilte!@? I have rc id€, dd do't eith Fy co- acrcsg the Htple 1@Iator. advlse a lrqulrT. I m1d f€] fre scisce lf I ug€d ttp last definltio' rhlch sLd toP The choice of base insulatars HllL dePend m ltBt ya aLl.d a total, hei8ht of 45 f@t with a 10 f@t totaL heiShL of 40 feet rith a @ find, vith ce@ic md tlass belng the best I€dirl8 disk, ed a to build ctpices fM lhe electrical standpoint, but the p@r- 20 f@t 6e. The latter uLd be a stirker ' est @cbanically. Cla$ iopreStaied epoxy j.9 very ed ru]d flap in the breze wl6s it cere Suyed pmctice il is Ede of stM€ ed qpssive' Btdle tBrdlood boiled in PaFf- re11. In a stid disk, wless fin F111 al,$ *rye HeLl, but is subiect to deterior- scres oa chicken rire supported ri.th s@ $rt of j,s rrh@pt' atis due to m15tw, s that j.t @y ned replacing ft@, inpaacti€1 and lhe use of a rcwd pieces fm tift to tioe. Re8anl16s of lhe @terial fM of Fire or tubing supported with crcss fast- hrhich lhe insulalors are Ede, ya shouLd kep tha ened to the lop of the rc!' is rcsl convenient. The on c1a ed spray ths wlth sllicme lubri.cill .egularly' ARRL Ante@ Handb@k hs sveraL illuslralions the cmstruction of top loadint sectims' In spite llhatevs ya do r@ber thal in$latlng @ierials of !D' @rks that the etema stFuld be 50 fe€t hiSh with the tend to be brj.ttle sd r€k in t4si@' ad tlqt lhe if possibl,e, I feel &yone wiII be stisfied f@! Hlnd l€ds at the bas'of you 4tm wiU be hun- perfo@ce of a 40 f@t @st rith 4I to 12 dreds of pouds, If y@ c& ilange b keep lhe in- L€dinA h@p at lbe top of i!. sulators in cmpressiq yd du be ruch sfer. The lie in ctplce ol @terials 1s bes! left to your m ir€enu- If y@ Are rilling lo sp€nd rcre cdstruction "L' FraunE1 Ar ltvenreo Aenrnl Ftaune2A"T"Aenrrl

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\ A'ru"" I Mast

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Fteune4 FrneIr YcuHlve Txe Tnees Fraune5 'ARRL"A-Fnmre lhsr Ano"Hoop" order to gve rc @ey, yd @ Bke yu 6 @t usll|t the 1-1/4" 5 drd 10 f@t TV @t exlci@ @ntloed above. Ihey @t l.4s ifa tEl.f 6 Dch a ttF lel,e$opiig @tst Unt vj.Il r€quire qN Suys b Eke UF wr drd stnLd be re1nforced vith a $ooden rcd at @h joj.nt. TtE sutS€tiG 6 bae j.n$lator, cl@trical cmiinulty, dd Suys ltrlch EE g1v6 for the el*opiJ|8 @t stsrld b€ follo-d nricketyn here t@. This Est ril.l, be pretty e Pl,4 dt the erectid in advffie. Hake 5N y@ fBve enqrgh guys, ild get angh help I yd @ fE ldle the @a84y sit€tim hdich are a]es! ceruin to develop. Cood luckl

If ya e fort@te enqrgh lo lEve re bit trees u yw yar{ riih msbLe spacing betEn th@, ya co gve evs rcre @ney by usirg lhe cGlruction of Fiaure 4. Pick lrc spots abdr! 45 o. 50 fel above tl€ gMnd, ad pside tfe rith pulleys md tEl- yaids. A top l€diig stMlure cosistir€ of sever- aI rirs held apart Flth 10 fot sp€ders is iso- Lated wittl iNlators, folldina lhe w pruedure I de$ribed above for the guys for the 61. Donrt forget that it wiU be EiAhty tErn lo cI@ the ln- sul,at@6 qce lhey re iNEUed, aid se 8@d mes to slat with. The vertical .adiator is a ,ire de- $ending fm lhe cster of the ]€ding 9@tj,o to the gtwd, irtEre it is acho.ed rith s in$lator. rlratrtl Thls rltl be a very eff*tive eterM if the tres e at ledt 50 fet or I apart, ed F11.1 stiU rcrk COUPLIIi6THE VLF AI1TEIITIA 1f tbey re dch cLo*r together, A vdj.st of this TOTHE TRAIISfiINER tt|@ @Id be t 6e a sir€Le trc wilb a sletlng to9 l@diia sti@, &d th€ halyarts bEtgbt dm lo BvEo pxrurps l{6lZJ re cdvoist Lrer level, sucb 4 tbe comer of a lp$e or 8rage. R@ber that trees od atere phen Iike to @e rud the sind bl.ffs, ild l€ve sciion Vol or use a r rynlg." I ? ,? paSe t0) di$uss€d enq€b sLack to alld for the @tio, eI* erem sysr@ desiSn, sprlng or pulley ed rei€h! b keep the Lins prererrtd:3119!!19 cru!rucrlo aDd lEtallatio sites. Eificj.st Effibly ti8ht. tnt. the * of i*- &!ffi ard fo. capljnS tt to tfE vLF trds- i.ltter tslll be yar "tre" ccideree h!re,-since tt"y r.u"-"11" If alt else faiLs yo @ aLBys @ke M strong Lnfluenc€ o the for & r'A-Fre l4astn rhich Es ruccess or trre ldniiiting*, foutring the desiSn subJect ul.t be fdhd ln a1.} of the ARRL rrTbe Radio A@teu's tiand- :3tiF. lr intrcdu.ed by emrnir,g" of bookn ard ARRL Ante@ Haldb@k editios before 1980. :f,"I"T.i:3].**rers the atem, io plivea ret,Ior lhe sizing of tne (For re dysterids r€son lhe A-f@ desiSn ls !,r)rng cqnponents and,t. the iEpedance to be cfrDled. @i.tted fru the n* handb@ks, qs thQgh it has nthe been old stedby{ for gsentids of haGl) Y@ a stDpl.ified rhj.ch 4s in llET l-1" ,i* of rhe el€t.j.€l prcp_ H111 need abet 60 feet of 2" by 2ils, ertles of a-typi€]. 50 f@! ttEse days of sky high lab€r prices @y 3ti11 be e ilt@ a! e olErattng Irequscy of 175 K\2. If tbe arte@ attractive Ey to 8o, aod ya wiU n@d 6uys ed rere ruted space b ictall tha, If yo @t a sin81e @t de- sl8n I suSgesl that stwn ln FiSure 5. the top ol the @t i9 equipped with a bracket &d inelator(s) to lpld the top l€dirt tep, ed the Fdiator is a Fire descsdir€ to the grud at tbe bas. Tlle saE preGutlm rith repect to the top in$Laior applis s 1n the previds 6xepLe, ad the guys gteld be brcks rllh i@lalors as deacribed fo lbe retal]lc Y lEt. ^j With sy of thse alterute ilte@ syst@ the we e of a 8@d gr@!d ad mdialg 1s j6t d ioportat s it ls sith tbe fre-stildirl8 tdq de$ribed first, f,- and thelr design ild install.atim slruId be sid- ered ln plming yow &leM,

I tEve oot lried to diss a]I possible rethdls of eie@ just to @ pointers I construction, but Bive ya @ u* in plein8 yar M version. If y@ are IIPICAL VALIIES IOR 50 i-MT A.IiTEI,,NA lucly @o€b b have space for a 50 f@t l@r rith Lots of €diaLs, Iruted ove. good miEt Brud, yd R. - 10 ohtrE to 50 otrds e goin€ to have a ELly klng sized si8E1. If C; - 150 mfd ya @rt @t aLl of tbese requi@tg, fclld the B?-lbe8ointo2meaottrE sugSestio 1n the begimingl up the ta].lest - Deoocs lut S 3:^"y..o 1 on surrcsorng !rcs, gtruclure yd @, as fr aEy fm tres I y@ @l nF - )uU orel \.tldius. etc- - with the best trud ya @ $rape totetherr ild R; 0.01f unr6 - usef;l radiatj.s resrs!&ce fith radials 1f possible. Y@ cart fail Lo grt et a usble si€Ell FraunrI VLl.AnrenHa,Crncurr ELemrHrs B

qer a perf@tly csducting grod plee, ed s per- systs. lhat ril] the pa@ters of yus be? Un- fect 1n$Iators, 1ts irtrrt irped&ce @ld cdsist of fort@tely there is no pmctical Ey of predicting ttE radiatlon regigteca R(R) in series rith the cap- the lcs, sd yo rilL just have !o do ydr besL to acltdce C(A), A3 dl$ussed before, the mdiati@ dinioize th@ by folLffing ibe practj.ce otlined i.n reslstue is a flctitlas .esistance rhicb, chen the trusiiti,nt ilte@ section. It i.s, tprever, dltipLled by the sqlle of the nF clJ!.tgi flqlng possible lo esti@te the €pacj.lance of tbe &telE, lnto the el@ temiBls, gives the va].ue of lhe &d b predict lhe radiatio resisbce pretly acaa- Ediated po{er, In this eFEple it is dly abolt ately. The estjmtion of antem €Fcitece is nec- 0.031 otre! Ihe €pacitece of the 150 mfd (pf) essry in oader to ple the design of the antenm wLd tepresqt a typical Lelescoping TV @si, nMted capl!€ circuil, ed the calculation of radiation vel-I aEy fM ey cooducting structures. the eff€t resistuce is e exercj-se in futility, $ fomlas cf the non-i,d€l installation my be sen fM the for €lculating tb@ are Biven bel@. other circuil eI@ts in Fi8ufe 1. First, the grwd systs rill have a resistance (R(G)) rhicb app€rs di- Calculalion of the eEc! capacit&ce of a short verti- rectly in series lith the radiatim resistsce ed the cal &lema, even for lhe ld€I c6diti6s where it &te@ capaci!&ce, urtb lypical values fM 10 ofre ts ]eated over a perfectly conducting grcund, anl to 50 oh!S, depending on lh€ lype &d rcisture conient Hhere i! is c@pletely isolated fM a}l othea ccn- of the ei], and the size of lhe grcund rods or mdial ductors which mtgh-- have ruL€l capacihnce r) ti, rs system used. This resisl&ce repre*nls a loss, &d difficuit dd no simple fomula exists. A rough ap- a very serious one. Note that evs if the resist&ce proxiGtion for this capacit&ce, ad one lbat is cd be held to 10 ohE it is sii.l] al.rcs! 300 tires ofteo quoted, is the following (I bave changed ii to the radialton resi.shce r od tt6t the @xinM effi- cl:t@ wftsJi ciency of such d etma c@fd be 6ly C.3 percent. In additj.on to the grund cifcuit loss, lhere ciLt be C . 7.359t1/lLoA\2\H/D) - 0.43) additi@l losses due lo &y €paci.bce betes the eLem ad swMding lossy @terials $ch s t€ lllEre: ed buildings. Ttlese are represated by a €pacit4e C(E) in series Hith a loss resistace R(E), and the C is the €pacitece j-n mfd (pf ) val.ues shom are onl.y a very m€h tpess based m Ey Lpg is the logdj.thn to the base 10 m obseryati@s. Thei.r effect is to inc@e Lhe H is the heighl in feet, ed capacit&ce of the etwa &d to introduce additid- D j.s the avemge dieter in inches. al loss. A fiEf loss rhich rust be included is the shet lo$ reslstece of ihe bas€ insu]abrs , dld 6y I bave €l,cuLated the value of €pacitece for severa] experisce i.ndicates thal a value of 6e or lF Eg- po$ibl.e types of eteM conductors, &d for the en- otDs is iypical for tood iNulators, ehile a ELue of Lire r€e of h€i8bts which ni€ht be of inlerest. The perhaps 100 K ohE is represfitatj,ve of bad m€. foutrir€ Table gives these eslimted €Fciteces for ttE wiN c@bi&ti6s of &te@ hei€ht &d &ten- l'ha al.l of these losses &d spurj-as €pacit&c6 E dieter I cssiCered. Note tha! lhese Efues are e sumed up, ttte etetm €n be represgted by the very apprcai@te, ard strcngly depend6! on the sur- seriea equivalent ciacuil stFm in Fj€ure 2. ondir€s, including effects of n€nby lrees, build- ings, pffr lines, ed other conducbrs. In SeneEI, act@i vaLues Hj.ll be sliAhlly larger due to these effets.

t-f 5 1r7z CAPACITANCTIII IT'IFDFOR nm(d ANTEI{IIAHTIGHT II FEETOF: AfiTENilADIN.iETER IO 20 30 40 50 (rncHEs ) 4 6R--> C,06{ {+14 wire) 23.\ 42.7 61.C ?S.6 95.'l Va.Lues for Rc : 20 ohE, RI : 2 @8otE, RE . 5OO otG C,102 {110 Fire) 25.0 45.4 64.6 83.1 101.0 Flauae2 r.00 37.7 65,4 91.0 115.3 13a.9 EourvtenrClrcurr 0r Arreru Ar ]75 KHz 1.25 39.7 68.3 y.7 119.9 1\4.2 A grod resistece of 20 otG, & i@lats rigt- ece of 2 oeSotE, drd the Elus ol C(E) ad R(E) 1,625 42.3 72,1 99.6 125.7 150,9 fM Fjgw 1 re used to cal,culate ttE vaLr s!|m; these va.l,ues represt a pretty Bood iEallatio. 3,00 50.0 83.0 113.2 141.8 169.4 lte equivaLst capacitee is I 75 @fd , ed tt€ totaf series resi.stsce is q3.7 otN. Arcthe. €y of rep- 5.00 i8,8 94.4 127,7 158.8 13t.7 resenting lhe et@a is by the shwt equi€fqt cir- cui! Lttich is als sfph, E@iEtim of !!F* Tbe dieter of 1.25 inches is lypical of c(mn l0 circuj.ls Fi1I sho! that lhe effsts oa gE$d resist- f@L !V @t extasions, rhlle the dieter of 1.625 ece, insulator resishce, ed LN Jue @ tre or inches is typi€L of the average dieier of a r-ele- brildings de ro€hly eq.€l. Ii order to incll€as scopiiE lype TV &Le@ @t of .J or )i. f-!t reidnr. the shtim efficiscy aU Gt be @nirized, &d Tbe dieter of 5 inch* is typj.€l of rhe sller tro ctEn *erythlr€ possible has beer, d6e this ef- self-$pporting l(rys, ficlency rcnrt be very hi.Bhl For this exaepLe it is lhe ratio of the 0.031 otn €diatih resishce to The €pacitance of a lop l€ding device is even !Erc- the 43.7 ofn series loss resishce, cr 6Iy 0.07 ea to sti@te. Figures in lhe ARRL Antema ilandisk percst. Dooit get discdraged a: :dis point; for shd tiE: for a $r-jl Crsk, the capaci'-d:e :s gi\e:. Fy m slatio the lcta-L lcss resrshce is abqrt 65 by the foll.tring apl.oximiicn: otms, &d the efficiscy is trIy au)u! 0,C5 percent, hlt I sti1l tet at pretty EII !

So far re have discussed a hypotbeticat eLffi llhere D 1s the dieter of lhe irsK, msured in fee.-. 9

A w cqvalat Ey to Ekc the top l€dirg devicc of the iltee 1s reffited with a $rles l€ding ylth 1n- 1s il a h@p cmlbaF to epport ltr ar$ tfE dEtor, {d a Btcblng netrcrk iE us€d ta ceple yul t}F capacltee prcDebly be pretty clo* to ttEt for twl,tlng lopedance {of the l€dlng coj.l ed at@ particularly the slid dLd(, lf weBl addtil.@l ln sles) to ttr tEnrlttcr. For u s&gle et.em {spok6n, pretty ylre, evs of sLl e addod. paleteE lf thc l€d1r8 coll Ere ls]6s th€ @t irpedance w1d be thc serj.es resistee gf rt3.? ofE. nr .adlatio Hj.gtace Ey b€ elculated by this [email protected]:

R(E) = 0,03t24 (rzt?5)2 rtZ5O)2 ot"" tRAniri rrr! R MATCH INC Lhere F is tbe operati€ fr€quscy in KHz &d H i9 the helght in let. Th.is yaLue is @rr@! fo. & a- E teM wLtlet €pacltive 1€dj.r€ at th€ bp. For a N TYr'OR{ ote@ vilh top ledinA tbe Fdratio resist&e j.s rnc@ed by the faclor

{1 + I(TOP),rI(BASE)) EBple: For 1?5 mld dte@ capacitece L = 4726 Eh aL 175 KHz ope.alin8 frequency. Hhere I(TOP) j.s the @st fl,trir€ at the tlp of the iltem ed I(BASE) is the crHt nwlng in the FrouneJ base. A very crude estj,Bte of this at.Mt Ftio @y be calculated fm Orelhv To CoupleArrerHr Aro Tnlrct'trrren

(TOP)/I(BASE) I : C(lOP)/C{BASE) lf the tr&sdtter opeEted fru a 15 volt DC supply rcltage thc rc voltage '10 acrcss. its tark circuit wl.d l.lhere C(IOP) is the top [email protected] €Facit4e, ard be abqrt rclts, and the rcquired lcd resistance C(BASE) 1s the ru of the et@ €pacltace and the m1d bc 100 otN for o atput pq€f of 1 Ett. TtE top l@dirE cpacltaEe, this I4t fo@la yiU give Etchhg retrcr* mld tbus need to have e lnDedance opti4istlc re$lt!, since uE fo@La for C(TOpl in- mtio of abqrt 2,3 to 1. llhile this ls a perf;ctly the cludes ellet of €pacitee t! the ut@ be- pEctical @pl,lng tectnique , It has irc udesiEble n€th lt, btt lt dG s!fi $Et w@ @d€t a@ts pllpertles. F1ret, th€ copooents 1n the @tcbirg gf-top l€dtng FiIl do 5@ gpod. For e$qle, if & retrcd( Ey bc qulte losy, iho€h for @ rhere I f@t d1@ts top t€dhg tpp predicted epictt,4e the required tmsltter 1qd rci,shce i.s grtq of 80 @fd 1s used, the Ediati6 E13tee of ltE ttEn the ete@ c1rcuit resistece the eteM @Id eEele ill@ riU b€ iEEs€d fru O.O3 otEr t, sbply b€ tapped dm 6 the tank coj.l, elini.Etj,ig abog! 0.C55 otE, dd tf€ Fdiated pore. eilt 8o up the @tqhing oetrcd<. Sec@d, the *lectivity, or ab- by 80 pqtat. Tttls ls rct & ea@ ctrvrge, but ft UiLy to reJqt ha|ulc Ediati@, ls quite p@r. FIU isre the 9tat16 ErEe by 40 percat ad ls this xiU ll1crw the po$ibuity of hatuj.c j-ntq- cetair].y rc.th ttE effort iffolved. feHce eltb brudest band receivers, ed undesired attstlo fM the FCC. To wrize aLl of thj.s, a typi€] etgu ril1 lod< li-ke a €Facit€n€ of abat t50 @td to 2OO @fd in one thbg rhich is a functiff of lhe etq@ pa@t- srt€ rlth a Eist2rce of pe!*Bps 10 otE oini@ to ere alse i9 rcrth @timlng at lbls point, The &- over a trJrdGl ofc @qr-. Alct aLt of ttlis re- te@ ]@ding @iL wiu rcl be lossless. If i.t has nO" slstace is dE to Is; ttE wtul (Ediatio) re- the Ether A@d (mtlo of Ectdce to series loss qU,y sista€ is aboft 30 Eilllotre, or il isjgnj.f- rcistance) of 250 the effect of ite loss xill. be b l@t 1rut16 of lhe total. TtE job ot the tudig add e additl@l sries lGs r€istance of about m.8 anC cqipfing c1ruitg 1s to trefe o uch o pos- otDs t€ the 43.7 ots of th€ basj.c e!ffi for a total 91bl,e of ttE tt@itts atFlt pqcr to the atgE, of 54,5 otre. Thi.s @ that th€ @iM &tqE 1n ordq to @Jdd4 tt€ wt tilich FilL act€tlv curut for 1 Ett t@sj,ttcr pqref inFrt @ be 6]y f]* in ttE radiatio |Bishce ad lhercby sd up 0.125 aqeE, tfF Fdlated pore. r1ll be 0,48 Dilti- belr€ tErelt!€d to ttF BId. If the trEltte. 1s Etts, ad th€ efficl@y B1U b€ oly 0.048 percqtt asded ta be 1m pcrcat efflciat, ltlich ls't t@ Tbis is abqrt lbe €se rith dy m stq@, ehich has optlrlgtlc, ad if the atput pq-. ls ra6rd b be a .rcared Loss eistace of abort 65 otE. Tt€ de- caplod !o the eteE ultb lm pet@t efficl,*y, 3i8n &d coEtructls of l@dint coils Bi.LI be des- Htlich Efft@tely is prerty ogtiriJtic, ttp all of elbed later. The only Ey b reduce tbe l,€ding @iI tlE pqs sj.l} b. di$ipated in tbe il!@ 1@. LGs 15 to @ke 1ts oon s tti€h 4 posslble thn€h For tlE sele otaG vith s16 ls of 43.? orE. wll€ a larEe dlaEter ald Flrdir€ lf Ylth tlp latB€t re Ett of t@itte poE pld rcelt ln a a- eire yo @ affor{. By lnq@ing the ete@ capa- t@ wt of 0.151 a4eEg, ard the Ediated pqcr cibnce thrqlgh us of top 1€d1ng its r€ctace, akt mld be abst 0.?1 trilliEtrs, for o deEll effi_ tsEe the ructece of the 1€dirg coiL, ulu be re- ciffy of al.y 0.0?1 perc@tl Ttp tgtsce of the duced $ ttEt for a givs 0 tbe actEl seri€ Loss re- 175 @fd is abqrt 5200 olre, s that fd this @t sistsce will b€ reduced. Thig is a sbstatiat added tlr voJ,tage dFp acrc$ it vflt be abdlt i8? vgl,ts. benefit ol top l@dl-rg. If the at@ rere to be @ted diEtly to the tl@itler atglt, this Eld rEed to be the rc Figw 4 sbds il €sier Ey to @ple the &teru to rcLtage acrcs its ta|k cir@it, and tfP DC spply lhe ll@itter, and ore I stM€l.y E(@rd, Id voltage to ttre flEl porEr aql.ifis ErId hare fo be vill find n@ros eroLs of it ln Ks CorcII's ,JLF over 1100 volts. Stch a i@itter @ act8lly be ScEpb@k. Th€ l@din& @il. i9 cmeted betFeen Lbe buil.l Fj.th TV ffiep iubes, bJt @st exFilEtss &te@ ed grod, dd is inductively copled to the ru]d prefer b Ao atl elid+tate, s re fom of lffilter by rulul irductace betreo ii ard the @tchlnt cLfcult is neded betF tte &t@ ild tank circuj.t, d stph picb.ially, The adv&tage of the il@itter, this caplint lehnique, cmpared to the previous one is ttBt trusitter I€ding (the l€d resistace cNp- Fj€ure 3 slffi fre Ey of @pL1ng a short &t@ to led lnto tbe ttueitief lank circuit) @y be varled the tmsltte. It 1s typj.€l of ttE circuj.ts used by cfqnginA the distece betre@ the tank circuit &d sitb a 150 Etq verti€i. at@, or Hlth a rcbi]e tbe l€diq coil, Fhicb st@ld ne be €Iled the cdp- &teM for &y_of the HF tho b6nds. The €pacitece lint coi1. targe spacing results in ,'l@se,' caplir€ 10

Ttlis discussio is dlrsted tmrd the design ed cmstruti@ of cdpling circu1ts, ed their adj6t- mi FiU. be dscri,bed l"ater. lbrever, a fs addi- volw 7 *8 page 15 tiqal, c@ts m @pUJ€ clrcuita re in order b@, llost slid gtate t.esitte.s ri,t} have a Fth- er Ie l@ded tak circuit "Qr' (the l@d reslshce or light. Lr&sitter 1€d.irE, rhil.e clo*r spacint j.n_ ror prcper pder atput rill not be ver5f ruch gr€td cr*€ the capung ed the !.mit!er podlr u!ut, than the ectece of the ta* circuit tmin8 rre.t@stfer @y b€ M at ey spply vollage ytEre €paci- tor) ed s@ r€djustment of &tetu tuing will be 1r rs.errrcls! M t,be porer alFtt (&d tFCe the reqdr€d s the coupfing is varied. To be sp€iflc, rnFrE I @y E *t co the d€lr€d value by s10p1y ad_ jEtina rl ire &Le@ j9 tsed to re@ce Hith very ]ight tb! copLlr€ . 1lr1s tmnaltter iay Ui i c@p1ing, as th€ capling is ieEsed it ui1.1 be o€- -rtn|( esffy to incr@e the lcdlr€ coil j.nduct&ce in or- der to kep the LuirE at the poln! ol qltM pog !-J.Y atpu!, Con&quently, the c@plete et€@ capli.ng a,lT;rr a clrcuit, @st lnclude re psisio for adjustlng this Tii|t M ITt ER jrg Couflrt a CorL tu , ed ylu. rct be quite ae siople as I haya sfffi. As d altemtlve to vafyint the j.nductace of t c ttE @pLiig coll I bave fMd lt covsiqt to ad- \/ jNt th€ eteM tuir|g by @€ting a viliabLe €pa- ADJUsT^'LE cltor acr$ (ouPrrxq lY either the rtple coil or Ht of it . Hhile guch a teinS Ettst i.rcEss Lire loss re- 3P^et{q /vAtir^BLf tut, ib is Dch qsier than hJildinA a copling colt nth vaiabLe lnduchce, at 16t in oy opinio. I I tEve r6tLy lEd the opportuity to test tank ffriTr P rmnnm re vililt^ vilil/|t/ll circuits bullt by l(@ Comell ltllltltt lllll//t/ttt L i^llErs ed by Jac.k Al,tbots of Pal@ Enginsrs. BoLh used a vsiabLe tuing core TANK CoYPLINq CorL FlGUi,E 3 fq inductece adJustent &d had very I@ los;, but the adjust@t of tming required very deli.cate vari- Fteure4 Ar Ersrenlhy To CoupueAtrelrr atlon of the positj.@ of the slug, dd I think the begtmer wUI tEve e €sier time lf he follqs ov grgtestlm. trasrstorized one srkj.r€ uith six volts collector spply or 1l Gy use lubes ad M at 3OO vollg pl.ate apply, and the l,@dlng coil oilL Ue tte s@. i'OrUy the coplinS ned be cmnged,', thile rhe @jor at_ rmcrrm rbr this copling ELhod is its sinpltcity,- ' rt atsb prcvides better hamrc sigml, redu;tim tban the firs! one, &d at rc added cost.

AilOTHERUSE FOR POSTIJOT.ES soror $ort-ha'*d eretm p6th0l0alongsr&theilrenmb6s.or seiionii m6ts cdr bs gr€srry simprfied bv drmrnoo rne.non*rir'ioJ'6#d'ro*tsrn ailbut a fot oriwdor th.m6t stmslotr re usrnorr.$tould hore ;;nr,q'riffi'u, m61s*ttd'' o.ri* iop-.lrJ,,iiifrirfiiri, vrrthdirt. Atni:m or.4: trd'.c ;ilrd;ii;i" r,* horspermd'nr, prweritins c!v'-lns.Eqrn bv eret|' ts fet r soof mct rritii #niiircrrron. r1.unttho t@ry or.r\€o m6tm ttpb6e Inxlrotor. our ne rp

BASIC 1750n TRTNSHITTItIGANTENNA

by ltl tchr I I Lcc

llcrconers to 1750n flnd a ByEtlqu€ surroundlng trrEsnlaalons on such r lor frequeacy. There ls no naglc lnvolved; 1750o reapouds to the sane physlcal prlnclplea thst rpply.to other frcquenclca. In thle rrtlcle re slll d{scus6 "loop" the transnlttlng (not to be confus€d rtth a loop of rlte) aad hoy to maxlnlze the radlaiad elgnal. The tr!osnlttlng loop conslsts of e loadlog coll, aa lnteoaa, and a ground.

For the purpose of developlag a uscful anteooa nodel, letrs conslder !n averrge clty lot 1750m lnstallatlon (ree Flgure 1). It ls constructed fron three 10r Tv oast sectlons ulth four 20' top loadlng glres extendln8 out horlzontally rt alI four polnts of th€ compass. The antenna stands on rn elevated plastlc 6lab that act8 a8 a base lnsulator. Beneath this ls I rater plpe and several Sround rlres that ruo out ln varlous dlrectlots to th€ property lioes rhere they are terolnated by 8' ground rods. There are ao bulldlngc or tr€cs lnyrher€ near thls antenna because the oHner/operator ueot berserk one day rith a Brush hog. The loading coll ls also located 8t the base of the lntenna.

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T-V r4A5r5F

Flgure 1. Typlcal 1750n autenua.

Th€ capacltatrce aa neasured betseen the base of th€ rntenDr and the reter plpe/radlal syeten ls 320pF. Aateonas of thts genre run anyrhere fron l20pF (30'vertlcal) to 500pf or trorc (30'verttcel ylth lots of top Ioadlng radlal ytres). llotc that top loadlng Hlrer.xhlblt 200pF capacltancc, rhlle th. vertlcal sectloo nh{.'l+ cootrlbuteG about 12OpF. The utlltty of oore top h8t capacltance rlll be lllustreted shortly. The reststlve coEpoDent of the lopedance (nodeled as a reslstor ln rcrter slth the capacltance prcvlously dlgcussed) as ueasured st the bese of th€ sntenna ls 40 ohms. The lnpedance brldge used sas a pretty good onel a rcslgtlve conpouent of only 40 ohms ls dlfflcult to fiad rhe! the capacltlvc rerctlnce ls 70 tlDes greater, or about 2,842 ohns. L2

ghll! thc thc 2r842-oha crprcltlvc rllctrucc lr earlly tuDcd out by ! 21842- oho laductlva tclctroc., rtlll burlcd 1o !h.t 40-oho rellstancc lg e useful(?) rrdlatloo rcrkt.occ of 0.025 ohog. Graphr ahoulng radletloa realatence for clGcttlcrlly ahort top-lord.d v€rtlcals era found ln varlouc englaeerlng lltcrrtur. (1r2r3r4). Flgurc 2 shorr ! schenatlc rcpresentatlon of the treorrlrrloo loop.

Lco,,- R..,. R"o",^to,.,

t. ftJ ,()Jr- . otl,a 71( ^, rooP I ,\*) 3t. orc-r- !6'^'"' Ru*r^,o

Flgurc 2. Traasollslon loop of e typclal 1750o lnatallatloo.

Ttc lort coooon trlnlnlttlog cchcoe ls e scrler tuned clrcult. It sffords a nanrgcablc drlvlng polot lopedancc Hlth tr.Dsolttcr voltages and curreats yell rlthln thc rcech of locxpenalve coopouentr. tlhen the lntcnna crpacltrnc. ls .rcrlcc rclotrat€d by the loadlng coll, Dothlag ls lcft but lordlng coll loss, redletlon rcrlstance, aud ground reslstrDcc. Thcrcforc thc transeltter thlnks 1t 1! dllvlog r pure reslctalcc.

Our loedlag coll deplctcd ln Flgurc 2 her e Q of 284. Q ts thc ratlo of lnductivc rcrctracc (2842 ohos) to realstrncc (10 ohos). Uhen the coll ls hook€d up to th€ llteana and ttansoltter the overall Q ts 2842/(10+39.975+0.025)-2842150-57.Q 1r alco rclatcd to bandeldth and la thls c.ac (1751.H2) thc bardyldth ta 175000/57-3kHz. A +/-1.51 Ehlft lo lntenna cepacliance ot coll laductlrce rlll drop thc output 3dB--half pouer. Slace trrDloltt€r charactcrlrtlca erc unkosn, thc prevlous st!tceeot la et begt ! vcry crudc epproxloetloo, but lt la ln thc brll park lod tuDlog ls crltlcal. If rc rrguoe thrt the clrcult l! resonant, rc cea further slopllfy as ghom lo Flgurc 3. R.o.. R6gtsltrox

j d:r ,OZS* :rx G\J 39.ozs,r- Rg"*r*,b Flgurc 3. TrrasalttlDt loop ln resoaaocc rcducer to reslstances. 13

Eveu thc Dost oon-tccholcal person can enalyzc Flgure 3, and Ohors ler rlll l8 neceslaty to suffl.ce for all of our calcul!tlonr, To rldtate a slgnal 1t porer dls6[p!t€ loEe cD€t8,y tn the rrdl!tlon rG!tstence' Rr. The ln thlE reslsiance (ERP) la glven by I'Rr. Assuo€ thet the transBltter ls 1002 current efflcteot (80 or 901 {s nore rePrcr€nt.tlvc) and calculrte the otrtenna for lU. Lz-PlR-ll5O. Therefore thc bcst antenoa current se cao achleve la about 141uA (.1414) rlth ltJ of poucr end e 50 ohm loop realstaoce. Letrg nake a table rlth vrrlous g,round+coll restatanceo and ehor hor| the entenDa currcEt ohos aod the telatlve slgnal rlll very. lU transnltter Poeer and '025 for radlstlon re6lst6'ee is assuned, and 50 ohos (a typlcal looP realataoce soneone on good ooll rlth sone oetal ln the ground) la our reference level. The radlatloo reslsteoce used for thls table lncludes that of the Yertlcal sect{on of the antenna on}y, and does not consider the effects of radlatloa from the top hat or the ground. ERP'ef fcc tlve radiated Pouer'

loop reslstance I (D,A) slgnal (dB) ERP

10 (copper plate) 316 +7 2.5nU

20 (copper soll) t/4 +{ 1 . 2 5nl'l

35 (nuch effort) 169 +1.55 714uU

50 (good sotl) 141 0.0d8 500uH

15 (ok) 115 -1.76 33 3ull

100 (bed soll) i00 -3 250u1

150 (no skyuave) 81.6 16 6ull

250 (rocks) 63.2 -1 100ull

500 (ftnd another hobby) -10 50utl

If you ruo out aad aeasute your aDtearla current and flnd 63.2n4, that doesnrt "Ioss." DeaD that your ground ls a totrl Your traosnltter efflclency oight be Ior, you could be mlstuned, your coll could be a loser, ot your RF aDoet€r could be ! basket ca8e. If you neasurc 224nA, dontt pet yourself on the back because evcn lf your enmeter ls rorklng, you oay not be radlatlng all of lt. Look at Flgure 2 agaln. Suppose re add aoure capacltance fron the basc of th€ aotenna !o ground. Not all of the current that florrs from the traDsnlttel through the coll rlll lnake lt to the radtstlon reslstatrce. sone rlll be ghuntea aray 1o th€ loss capacltance. The stray capacitance doesn't dlsslpate poeer, but tt does dlvert curreot euay fron the radlation reslstence and iherefore decreases the radlated slgnal. Excesslve base caPacltsnce 1s caused by lusuffLclent base lnsulatlon (oeparatlon fron grouud), and uon-v€rtlcal feed llnes ruonltrg fron the coll to thr lnteona.

Trees, uearby attuctures aod Detal objects (such as other ![t€D[A nlsts or rlres) stll abeorb energy or act 15. shteld, robblng the stgnal of lts preClouS fes nlCrorratts. Other Iossco ouch ae lcaky lDsuletors r conductlve guy rlres/ropes, and losses lu the conductors thenselves, such ls sklu effectt nos-copper aoteDoa conPonentsr thtckly-Patnted or rusted surfaces, aod poor conoectlons, take thelr toll on the rvallable pouer. I4

Yhy lr r horlzontal rotenna eo bad? Provldlog ve take steps to reduce all of thc loac f.ctors, rhy doeg e horlzoottl eDt€lre haye 6uch ! touBh tloe r.dlrtlog, r rlgnal? Horlzontally polorlzed elgncle rt lou frequencler ar€ grc.tly ebsorbed rs they travel eloog the aurface of the carth' If the slgoal rr3 rrdt.ted vay up ln the sky (Dlle! uP) thea thts effect would be nou.xlstaDt. Vertlcally polarlzed vevet lre !lso attenueted as they trrYcI elong the carth'r lurflec, but not nearly ao ouch ra horlzontrlly polarlzed rrves. Thercforc, rtlck rlth a vertlcal aDteona.

Top hat! lcrve tro fuDctloor. Flrst, the hrgcr the capacltance of the top hat, the Brertcr the eff.ctlye helght and rtdlatlou reslstance of the antenna. Thc .025-oho radlatlon rcrlatance la a luoped con!tant th!t ts bascd uPoo unevcn currcot dlrtrlbutlon ln the lnteDna. ona nuBt reallzc that the actual radlatlon reslstanc€ of the antenna ls dlstrlbuted throughout lts IeDgth, as 18 the anteuu capacltance. Therefore, not aII of the current floulng lnto the base of the anteooa oakes lt to all of th€ radlrtlon reslstance, or to all of the antenu. A large top hat wlll act to hog current fron the vertlcal !ectloa. Iu thls exanple, a fractlon of current (200/320pF-62.5%) flovs through lll of the vertlcal radiatlon reslstaoce aud nakes lt to the top hat. The reoalalag tzOl320=37.51 of antenoe current flors through only part of the vertlcal radlatlou reslstance. The blSget the lep hat for auy glven vertlcal, the lErgcr the EFFECTIVE raqlatlon reslstance. The 0.025-ohrn value prevlously uced ras en effectlve rldlatlon.resl6tance and accouots for uneven current dlstrlbutlott such thst O.025Xlt ylelds the proper uunber for effectlve r.dlated porer.

The secood beneflt of larget top hats 1s that the lncreased anteona capacltaoce rlll result in a proportlonately grallcr loadlng lnductance. Less lnductancc neals less coll loss reslstance, rnd less capacltance from the physlcally snaller coll to grouud. lf a soaller coll ls used, lhe loop Q rtll drop oaklag tunlng less crltlcal. ADtenna voltagc ulll drop as cell maklng , for less strlogent lnsulatlon requlrenents.

The aoalyels above has beneflted fron e fev ossunrptlous and has obtalned Bome nunerlcal values (antenna/top hat capacltance, effectlve radlatlon reslstance) fron foroulae oot shom here. Houever, calculatlng theee aumbers for any glveo aotenna ls a tedlous and useless pursult alace there are so oany effects thlt caooot be quantlfled. Uhat le ahoro rlll serve as a reference fron rhlch reveral coaclugloos nay be dravu regardlog optlnlzlng a 1750n aDteooa. Before ya Etlte the conlcuslono, lct ua couslder ooe last blt of lnfornatlon.

Our digcuseloas assuned a flat top hat. In. EoBt lnstauces a flat top hat ls lopocelble to coostruct oulDg to a lack of support structures from shlch lt oay be euspeoded. Varlouc rtudles have ahor thst for drooplng top hatst the leugth of the conductora oay be extended untll thelr eods are at epproxlnately 1/2 the helght of the vertlcal aoteDna. Beyond thls polot the top hat vlres begln to exhlblt a ahleldlng effect on thc prlmc radlatlng portloD of the vertlcel, thereby rcduclng the radl!ted slgnal. Lorfer experlD€nts have shorn that a 10i vertlcal clth a flat 40' radlue top hst does Dot radlate as rell as r 40'vertlcal ulth a l0r radlus top hat. Glven the 50' (15n) antenua Iength (vettical+top hat radlus) restrlctloo of Prrt 15.112(c) of th€ Fcc rules, a 20' to 40' vertlcal rtth the belance lD top hst ls optlnutr. ltore exactlng gcnerallzatloos are purc speculatlon. A polnt ls rcached uhere nuch depends upoo the lodlvldual transolttiog slte, ground condltloas, aod the cherecterlstlcs of the recelvlng setup. ' 15 lf refcty lsd conventcsce are an laauc, the 20'Yertlcrl la optlrun slncc oue pcrson c.n tr!lly crcct 20r of TV nact. A 30' vcrtlcal rcally rcqulrcr 2 peoplc or lorc. 40r requlrer ao tntenn! Prrty. Ar eo cxauplcr crlctlsg thc 45r LJIH bcrcoa vertlcel (rlth a apokcd top h!t) took 11 people. It rtt conrtructcd froo 5'sllltery thtck-rall aluElnuo 6ast 3€ctloB3. 3 pcoplc Itftcd th? rrlt rt thc base, a fourth persoD Polltloncd tnd lnlart.d the DCxt scctloo, ead 6 othcr persons fcd out 3 acta of 3 guy roP€s. Thc clcYerth per8oa ren rround oonltorlnS thc leau englc. 6 oonthc letcr a gartlculatly rlady storB coapresaed th€ lrttcoa. untll lt bored {o thc ccatct, and uPoo aprlnglng back loto lhrpe' go auch uprard vcloclty ua3 8€nerated that thc eotlrc rnteua! dlalotegrated lnto 5t lectlora dlsttlbuted all over the beck ysrd. All guy'rope aochorc aere ltlll ln placc aod only ooe or teo .eetlons shosed lny slgns of ltress. Vlerlng such a apectacl€ rt the bsse of thr auteoM could have beeo a Dost iopall.ng, .veot. trortuoately, the hot tub ee! vecant at the tiDe.

Nor for sooe rules of thunb regardlng 1750n transnlttlng antennae:

1) Put as Duch copper lnto the tophrt as posslble. Reneober, doa't let the top hat droop further that 1/2 uay doun the vertlcal. Try to aaltrtaln geooetrlcrl syen.try lo thc top het lor oaxloun capacltance pcr foot of conductor used.

2) Try to use copp€! throuS,hout. Copper plpe cao be bought ln conccutrlc alzes and brazcd or soldered tog,eth€r. llslntrln the lotegrlty of each copper-to-copper connectlon by solderlng or Jolnlng ulth sheetoetal screrg and coverlng the connectlon rlth RTVor other aultable.elllcone sealant, Tv Dast cao be ehunted by copper ulrec to locrease conductlvlty, and e cage of vertlcal rlres caa be substltuted for a oast rhere the roteDoe la auepended.

3) Contrect as oaoy Detallc objects and grouud rods as possible to the ground systen. Optlnum radlal length ls sllghtly longer thao the antenna la tall. For a 30'vertlcal, ten 40' radlals oake a better ground than one 400r rtre.

4) Use an efflclent coll. From the conslderatloos of Flgure 2, a coll Q of. about 50 (57 ras the overall loop Q) uould resul! ln an imedlate loss of 6dB. The use of Lltz rlrc vs. enameledulre la worth r factor of 2 lmprovement ln coll lose. Ferrlte loadlag ls useful for produclng Qs of 250 to 350 aod phystcally snall colls. A 7.5"X0.5" type 33 ferrlte rod (avallable es part nunber R33-050-750 fron Auldon Araoclo tcs, 12033 Otsego Str€et, North Hollyrood, CA 91607, coet ls around 13.50 tncludlag portege) ls rb axcclleot cholce for loadlng colls. 100 turo8 or ao rlll produce a oaxloun laducteoce of 5 or 6nH chlch cao be tuned by rltdlng the coll around the fcrrlte rod. "basket" Large alr-core colls or colla arc probably the best, aad they ceo exhlblt Qs ln excess of 600 ln the 2 to 10nH range. For the eurloul, a ratlo of 2.5:1 dlametershelght ls the optlDuo geonetry for auch a coll. Tuolug . basket coll ls best eeconpllshed ulth . vrrloneter.

5) Uge !D efflileat ttausolttcr. lt! efflcl€ncy can be dcterolaed by oeaeurlog the ratlo of output poecr {loto a load rcslstor th!t le approxlnstely the saoe value es thc loop rcslstaoce) to the DC lnput por€r. You ulll aeed ao AC voltneter rlth cnough bendrldth to covcr 1750o (ot an RF anneter) to o€aEure the output pouer lnto ! reslstlve loed. Replace thc loadlog coll and anteuna rlth a clrbon coopooltlon reslstor! untll, r veluc lc found rhlch results lu the sane DC laput por€r as ras obse:ved uhen op€rrtlag t6

lato thc coll/rstcnu. Porcr tloSFET trauaoltter clrculta vlth 80 to 907' cfflelcocy c.D bc coErtructcd.

6) Urc hlgh-qurllty lusulatloo throughout. A I' porcclalo base lnculator lt Dot ovcrklll. In rddltlon, pyrex or ceraolc rtraln lnsulators lre not ra cxcclr urcd la rerlcc ylth Dyloo guy ropc8. Do oot urc Detallc guy vlrer. Thc top hlt oflcs subrtltutcs r! prrt of th. top ret of guy ropcs. It has , becn fouud thrt polypropylcoc guy rope deteEloratco rapldly rhen cxpoccd to ruollght. 0.1" oylon rccd-cat.r lloc hac e uecful llfctlne rDd yct l! lor- profllc rad llghtselght. Thla oatcrlal can be purcheced ln bulk !t nost herdrarc rtorca. Ecrarc of PVCplpe. Tcala coll tcrtr thos thrt rhll€ uhlte- colored PVC ptpe lceoa to be .D ld€quate lnaulltor' Sray (end perhaps other colorc) PyC plpc lc very losey. Do not uae gray PYCplpc for coll foros or loluhtors. Uae othcr colorc et your ovu rlsk.

7) Tune your loadlog coll frequently untll you have an ldea about hos the systcn tuolag varles rlth tlEe, season, and reather. llost alr-round loadlag collr dctune rheo r haod 1r brought clthln 3', aod eone are even Eore "teo-foot ecaaltlve theD thls. Tune slth e proverblal pole." Observe your tuDlBg by rltchlot ratenor current (neasured ln llne rlth the anteBua ltsclf), a neon llop, or r fleld gtrcngth neter. Ao aEmeter and neoo llght rlll cach trke a soall eoount of pouer, but ln oost cases lt ls lnconsequentlal rheo coupared to the evalllble porer. For lDetrnce, au RF aoneter nlght take 20Eli or poret fron a ttausnlttlug clrcult shlch has an avellable pouer of 800nll. The lora ls lbout 0.l1dB. A frlend rlth ! recelver .ad e telePhooe cro ' provlde excellent renote fleld streog,th Deasurcneots.

E) Locatc the anteona ln es clear a locatloa as posslble. A oountaln top la best; lcanlng lt up agalDst ! oetrl barn in thc bottod of a canyon ls thc 'rorlt. Keep the area ocar the base of the anteona clear of bushts, fences, bulldinge, aud other lossy capecltaoces. A clear atce rlth a dlaneter equal to the ttclght of th€ vertical ls a plus. Bulldlngs, pou€r poles aod other lnteuEaa lre th€ ror6t offenderc. Iu a rcsidenthl slturtlon lt ls best to locate the lat€noa on the peak of the roof. "Flgure 9) Tif, to reconstruct a 3" for your lDstallatloo. Glven the Q of Lhe coll eod flgures for the traosoltter output poner and loop reslstaoc€ thls ls €esy to do. Inspectlon of Flgure 3 ulll glve an lndlcatlon of rhere sooe lBproveoeDt olght be nade. For lustance, lf the coll loss le 10 ohns and the ground loss ts 90 ohue, your extrr Lltz rire ls better utlllzed !s ground redlgla.

10) Keep your beacoo runnlog 24 hours e day, 7 days a ceek. There have becn rclatlvely fer reports of geople hearlug beacons that uere oot runnlog.

Refereocea rorth readlng:

1: LF Euglneerlng Coopany, Catalog No. 100/Fall 1985. 17 Jetf.ry Road, East "Lor Haven, CT 06512. See Frequeocy Englnecrtng Data" for equatloos and graph of redlatlon reslstance. Thls oaterlal ras credlted to ADteona Eagineerlog Handbook,by Henry Jaalk (a classtc text on the gubject).

2z Rf Deslgn, e nagazlae pupllshed by Cardtff Publtshtng Conpany, Inc.' 6430 South Yo6enltc Street' Englerood, CO 8011r. (303) 694-1522. See the "CaIu, January/February 1984 artlcle Capture Area, and Transmlsslon Loss for 11

Grouudcd llooopolrr rnd Elcvetcd Dlpolcr, Prrt 1Ir" by Joho g. Alee ead Ullltel r'dcrlvatlooh A. Edroo of SRI Iutcroatlon l, llcDlo Perk, CA 94025. Shora of cqu!tlon lor redletlon rcal!trtrcc of ooaopolcr (rhort vcrtlcal enteaaer). Thc tltlc eouoda laauffcreblc, but lt ts tcllly . rhplc ertlclc rlth cqurtlotu thrt .oyolc rlth r ealculator c.n put to uac.

3: Rrdlo Eaglncctr' Handbook, by Fredcrlck Ennons Tcrnen, Flrtt EdltloD, 1943, publlahed by llcGrar-Hlll Book Conproy, lac. Thlc ls rnothet clrerlc eod lt br8 .o .rc.ll.Dt aotcnnt scctloa rtlrtlDg oo pagc 710. pegc 194 la cspccl.lly uacful lf you crn flll la ell of the nuobers ln ble cquetloot

4. Nautel, a Caoedlan NDB unufacturer loclted in Nova Scotlr, hel ra cxc.llent auppleoeot thrt tr lncrudcd vlth evcry NDB lngtructlon uauual. ?lrey rere klod eDough to send oe r plrtl.l copy of e nauual and thlr rupplcocat "NDB uhlch lr entltlcd Antenarc." It lr .D exccrlent rule-of-thuob aourcc of lafornatlon. The fornulae are rlople caough to be rorked out elth pencll ead paper' lf oot lo your head. r rtll attcnpt to lecure perolcaloo to plaglerlzc thlc docuocnt lo the futur€.

SKY,August1987 (see p@ 4l ) 1A

OptimizingThe Part 15 Antenna by Mifrc l}trJde|r'e22 produced a further increascin signal strcngth, but thc Early in 1986, my 30"ft. 1750m transmitting increrncntwas smaller than tlut otrcrvcd in thc 8 o vertical was d€stroyed by high winds. Repair or l3-ft. stcp. Signels were still gencnlly marginat immediatereplaement wrs impoesiblc,rc I decided bcyond 100 miles. By this time thc scason had to make whrt I could out of the wreckage while progrescd to the pdnt where nights werc largely gathering rcsourccs for a new and bettcr antenna. clobbcred by QRN, so cvaluatioo w8s limitcd to During the monthsthst followed, I built and testedr groundwrve pcrformance. scries of very short tophatrcd verticals. ln the Antenne No, 4 moved up to 23 fect, with a, following parsgrapts I will describe my progression correspondingtrim of thc longer tophat elemcnts back to a full*ize anlcnna. In mncluding, I will This step finally brought signalso a level where I diruss some of the practical and theoretical oould sustainconvcntioul CW QSOS beyond 100 implications of vrrious tophaFto-verticalratio6. I miles, but only when noise lcvcls wcrc low rt thc apologizefor not havinggone Metric wilh this work. receivingsite. I have used the old measure of 50 feet as the Antenm No 5. The finel st€p in this progression allowable antcnna dimension, while it is aaually was a 36 fmt vertical with 16 tophat elements,ctch l5nr. or 49.2 feet. 13 ft. long. Signalsimproved considerably(on rhc The Sile is a narrow brushy ridge at 2,000 feet order of 6 dB) over th€ 3 ft. antenna.This large elevation.The ground systemconsisis ofaround I 50 improvement may in part be duc o femtical insulatedradials, most of which rangefrom 30 to 6O anendon paid to the elecrrical continuity of $re linsl feet in lengh. The earth connectionis composedof antennS. 20 copper pipe grounds.each pipe being driven rs Resutts-There are no surpriscs here. Tallcr deeply as possibleinto a treated posrhole.Ground antennaswork betterthan shorterNntennas but short resis[ancemcasured at | 65 kHz is around l0 Ohms. antennas still radiate. Even the 8 foot tophattcd Anteone No. I wasan 8-ft. verticalwith 20 tophat vertic{l will exhibit performancc superior to elements.Eight of theseelemenls were l4 ft.,8 were horizontal wire lntennas of Part 15 dimensionsat 36 ft. and the remainingfour were 30 ft. They were heightsup to at least 30 feet. This result probably arrangedin symmetricalpairs and securedto I pole would not obtain if the vertical were obstnrctcd or if and rigging support that surrounded the site. All the ground systemwas poor. tophat elementswere ess€ntiallyat 90 to the 8-ft" Tophrls-The tophat plays an €ssentialrole in mast. short vertical performance.To look at an extrenrc The large, low tophat produced a high antenna case The 8-ft. vertical with no tophat will requirer capacitanceand in mns€quence,only 600uH of loding inductanccon the order of 20mH. (Compre inductive loading was required to resonate the this to 0.6mH with the tophar). Coil losseswill structure.Tuning was broad, currenl was high, axl ineviobly be high. lf the coil is any good at all, rhc vollage on the vertical was low. systemQ will alsobe very high.This meansthat there Lmking more like a cartoon than a functional will b€ high volhge on the antenna and that antenn4 this stubby mushrmm actually functioned bandwidth will be extremely narrow. Tuning reasonablywell, being only 13 to 15 dB down from becomesvery fusy in sucha situation.In fact,remote iu 3&ft. predecesor.Copy of the CW beaconwhile tuning might be necrssarysince the presenceof an mobile-in-motionwas comfortableto about 30 miles operator within a few feet of the antcnna would and possibleto 50 miles.At 100 miles,the copy was hopelesslydetune lhe system.Wone yet, even if a virtually impocsiblefrom casualroadside stop but at perfectly tuned and completely losslessloading ll0 milc on a March night the signrl surfacedo inductancewere obtained,the effectiveheight of the copyable levels every 20 to 30 minutes despite antennawould only be 4 feet.With sullicicnt tophst moderatelyhigh levels of manmade noise. At I20 the effecriveheight can bc broughtso close to 8 fectss miles Jim Ericson'ssampling recorder caught the to make no practical difference.This is to say that signalmany timesduring tbe week it wason the air, virtually all the availablecurrent will be flowing in. but rarely, if ever, at QSOable levels. the entire vertical element. The result will bc a Antcnns No. 2 was a l3-ft. vertical,prodtrced by modestbut usefulamount of radiation. adding a 5-ft mast section to thc No. I venion. Flgure I illustratesrhe eflectiveheight obtaincd Maximum tophat radius remained36 ft. SystemQ with various tophat-to-vertical ratioe. Values of increased.More loading induclance was required. effective height have been calculated from the Tuning becamea bit sharper.A dramaticincrease in formula: c signal strenglh was oberved. The signal becrme 9M marginally audible in Nevada,280 miles to the east he=h(r-tt-r=_l) t[Yl - "H and occasional pesks to QSO levels were noted at 120 miles. h is height in feet Artennr No.3 extendedthe vertical to 18 feet. C* is capacitance Tophat elementswere pruned to keepoverall lenSlh of vert in pF within Part 15 dimensions.The increasein height C, in capacitance of hat in pF T9

Whilc wc arc, unlbrlunrtely, restrictedss to tophal lengtll tlue is no limit to $e number of tophat elerncns ttut mry bc employed.Thrs, it sbould bc p6iHc to obuin somcimprovements over th€ csedr illrstratcd in Figure I by increasingthe numbcr of clcrncns. As more tophatelanents arc deploycd,we bcain to comc up aginst diminishing returns. As the numbcr of elcrnents increases,the capacitance pcr foot of cach clcment dccreas€s. The 16 tophat clcrncns on my finrl antcnnaare only contributing rbout 0.7 pFlft dismal in comparisonto tbe 2 to 2.5 pFlfr thst would have bcen achieved with 4 clcmeots In my casc,this reductionin capacitanc€is duc both to rhc large numbcr of closcly spaced clemenband the fact that they form an angleof less tlun 900 with respectto the rust. I might havedone bettcr to concentratemy ellort on 6 to 8 horizontal clemcnb than lhe larger number of sloping tophat Flg. l: Elfective Heighl/Physical Heighl *r res. ln any casc whencvera.vertical ofless than l5m musl be risdJ, it will be a positive advantageto In all cases Cm was assumed lo be 4 pFlft. Ch emplo,r-the remainingavailable length in tophat- a.sumcs 4 eq|lall) spaced horizrrntal wire lophst gnd thc nxrrc lhc brttcr, within reason.Verticals of l0 elementseach having a capacitanceof 2.5 pF/ft. feet and lesscan be usedm someellect on 1750 m A represenbI vertical of from I 0 to 50 fe€t Curve and suchantennas will reapmaximum benefitfrom a having a lophst radius of 50 ft. in all cases.No massilc tophat.Howevcr, they cannot be expected to ofcurve A is acceptableunder Part I 5. configuration yrrform very n ell in the absenceof a well developed though by the time the vertical is teduced to 25 ft. it is ground plane or if they are not in the clear. apparentthat the excessivctophat radru buys vcry little advantagein effectiveheight. Refercnres: "Part 15" antcnnawith Curve B reprc€nts a ' Basic I 750m TransrnittingAntenna,' Mitchell radiusvarying in proportion to h€i8ht fu thc lophat lrc Thc llwdown, August 1986. tophat radius approachesand excttds $e vcrtical 'Notcs on 1750Metcr Transmitting height, physical and elecrrical height becomc very Antcnnas/Grounds,"Vince Pino, The Lowdown, similar. January1984. Tophaned verticals in the 35 lo 45 foot rrnge "Transmitting Antcnnas for 1750 Mcten," E. rppear to be oplimum Part 15 antennasfrom an Phillips,The l.owdown,July 1980. cffecrivebeight standpoint. However, theit advantsge "Coupling the VLF Antenna to the Trar$mitter," ovcr a SSfL pure vertical seems,at best, to b€ E. PhiUip. The Lowdown,August 1980. minimal. The tophattedantenna may prove inferior *NDB Antennas," Nautel Engineeringof Canada. to the vertical if the sacrilice in height resultsin a radiator thal is iower ihan surroundinSob6tructions. Mike Midcke is Propagation Editor for The Sincethe electricalheight of a pure venical that is Lo*dowtt lruerestd persons moy write to Mike very short in terms of its operating wavclcngth is Mklcke. hx 123, San Suneon, CA 93452. about half its physicalheight, the mmt a tophatcsn aocornplishin this respectis a doubling of effeclivc heighr Even this will not be achievedfor Part 15 antennaslaller than about 30 fr. lt would app€arth8t sucha doublingofelectrical heightwill produceonly a 6 dB increas€in field strength.In actual pradice, benelis are somewhat greater-'and somelimes much greater.This is probbly becauseaborptive lossesin the ground, vegetation,and sutrounding objeos rapidly decreN€ as the radiatinS conduclor is elevatedabove the aborptive materials. However, there are good rcarcns for increasing antenna crpacitanc€ b€yond the point where electrical height approachesphysical height. Loading inducrancc can be reduad. with a conesponding reduction in resistive and capacitive coil lo6ses. System Q will be lower, resulting in broader bandwith, more stabletuning, lower voltageon the antcnnaand les stringentinsulation requiremenLs. 20

NOTES ON I75O HETER TRANSHITTING ANTEXNAS/GROUNDS

by Vincent J. Pinto 'beenI I've doinq a lot of erperimentino rrith t75O meter transmittinq antenna srfiqurations letelvr end I fiqured l'Il try to 5hare some of what I and others have leemed. To save you readine all the verbiaqe that follows, I'll qive you a gartial sufimary in e nut:hell - the first two points a garaphrase of what Hike ltteideke said so.ne months .qo in a Mailbaq Letter - GET THE ANTENNA AS HIGH AS POSSIBLE - and GET AS l.tUCH CAPACITY AT TEE ToP END AS FOSSIBLE. Third point - OSE AS GOOD A GROUND STSTE}T AS UU}IANLY FOSSIELE.

First offr qet your vrtenne es Noh es Docsible. If vo.r can only qo 28 or 30 feet hiqhr that's OK' and it WILL radiater but it i.rst won't be aE qood es possible, If you want the bestr every last foot cotrnts. So that meanB 34 feet is better than 32 feet. And worth everv bit of the effort. And 49 feet is better than 46 feet. Andr aqain worth all the extra effort, Siqnal improvements due to heiqht increases will be even more eraqeerated than for ideal installations if yor.r antenna is not in the clear, butr like mine, near houses and tall nearbY trees. Here you not onty aet an increase from raisinq the effective electrical heiqht of ttre antennar but you qet more of the cr.nrent-cerryinq gortim (which is what radietes vour siqnaj) of the tower rbove og51rtgs. I,m speakjnq frorn hardcore .rgeriencPr not irst theory.

If you can't put tD a onventional free-standinq or quyed towerr consider the cheap end easY wev. Cap llossfietd was able to erect a decent vertical with tophat by throwinq nylon 'antenna" rope over the topE of two nearby tell trees. At the end of each thin roger h€ rttached a piece of wire with an insuletor between th€ nylon line and wire. He then oulled w the two nvlon ropes by the far end etld ttre center r+ire becarne a horirontal tqhat. The verticd tntennar about 3l' lonqr droDs down from th€ center of the toohat. So th€ two trees suspend the vertical and tophat between thern on nvlon ropes, Cap re:invented what is probably an ancient tool to do the ilb of aettina a lenqth of nylon rope over the topsr or near togs' of tall trees, Reasoninq thatr like mer he could never throw a weiqht with a rope attactpd hiqh enouah to make it over the branchesr he used a verv efficient slino to lamdr the thin rope. Cao ties a small e{eiaht (e brass plumbinq elbow} to one end of the liner coils the remaininq 100 feet loosely in larqe coils in his handr and with the other hand starts to whirl the weiqht in e vertical circle (the weiqht is abotrt 18. frorn his lwrd), llhen the spinninq weiqht has gicked tp enouqh ggeedr it is releesed toward the terqetr cerryinq the rooe behind it.

TOPSATS. I discovered the more toohat the betterr at teast to the ooint where the tophat radiu: is elmost equal to the tower heiqht. Of courspp tou have to stav within FCC oert l5t but so.ne tophat is better than none. ln a clear areal where thB tower is not surroulded by nearby obstades that €rtend uo .n apDrecieble part of it's heiqhtr the'nrost ytrl cin qain from e tophat is d dB. If yor.rr tower is swroulded by nearby obstaclesr mrny rt lcest l/2 to 2/3 as tall es the towerr you can aain a11p7ssis5ly more bv r.Einq e toghat, Derhtgs up to .bout 8 dE. Sinrplyr en r-rrhatted vertical {of the kjnda lengths we user and at these frequencies) has full orrrent et the beser end rero onrent at the too, Ttre crjrrent distributim frorn bottom to top is linear. This is the sarne as savinq thet mFhalf of the tower is carryinq full o.rrent (the lower helflr and one-half ig cerryine no (th€ oJrrCflt top helf). l,lhen you add toghat capacity, you can make this distributim zJ.

nmlinear' and'pull" more orrrent into the top half of thp tower. For e towrr not rhielded 'dor.tle, by obstadesr th€ rnoet e t@hat crn do is the tower cffective lenqth, {In . shielded you qain situetim, cpre because you finrlly qet e tower Oortion above tlF olstrrlps to reditte r riqnificant rrEcr|t.f

As to many artides have :aid before, it is not necegrlry to have horizontel tophets. This is ideal but I have discovered that even sharpty enqkrd r.rnbrelli brirps rulninE frsn the too of the Yerticd, point (well-insulated - even to a of cotrrse!) nerr th€ grorld rnd mlv t€n - twelve feet frmr the base of the tower hetp a lot. tf you ere utine wires ls tophatsr you'll find point the of,low return' appeirs when you qo geet .borrt 15 spokes or wires in different directions. If usinq wire tophet radialsr it is frirly inportent that th€y be equallV Bpread over the conloass, If a siqnificent number tend to qo in one dir€.Etim, seV EaEtr horizontd cirorlatinq oJrrents will qet drwan into the tophat and be redieted, Hhile this may look like an inprovemeot on a nearbv field strenqth meter, oieven one llz mile awavr it's invariablv a killer at further distances, At the kind of heiqhts end lenqttE we use in our ant€nnas on this band, horirontel redirtim is cnly r loss fector. It nev€r, makes it to the horironr much less beyond it!

GROIII{D svstems are hiahlv inportantr €Epecirlly if yor.rlive in an eree with goor BoiI condwtivitv. Gro-rrd rodsr at teest two or three cooper or cDpppr clad rods e f:w feet apart and at least fivp feet deepr lre e minlm.rn n€cpsBitv for liqhtninq protection' and strtic Thev barelv start to do the i:b .s en efficient RF qround at 175o, bonre qror.rro radials lre a mustr and the .ore the better. Each rediel slsrrd ue et tea:i er tmq er ttp tower heiqhtr and twentv redials ere r qood co.ngrornige between performance end hrrd work, BV ell meens, you're if so inclined, put in ,Dor€ tike 30 to 60. It f.lll.l. help. Rediels work better if terminated qround in rod: at their far ends. Terminatinq er.n r few ie better than none. The rrdirlr fi|ay lie on the swfacer or be buriad me to a fcw inchei in . nerrow slits rrrt in the roil with a rherp Ehovel. If you live in rn area of poor toil condwtiivitvr or qet irst want to out better (rnd tNr rnethod nEALLt t"tprl, cor,rio", buvinq a few rolls of qalvanired her chicken fencinqr perhaps 2 ft. bv 5o ft. rechp or 3 ft.by 5O ft.r and spreadine these or,rt near the bese of the tower to m.k' r ar;d sreen. . I reomrnend placinq them yot qrot'd over r radials. Thev cen be held in pi"i", t'.,O U"to, lawnmower blades) bv makjnq short trooked nails or strpleg in e J shioe otrt of t2 or ll qaue qalvanired fence wire. Of cDUrBEl attach eectt $reen to tlp qrornd Eyitern entrd tie point at thB tower base.

All GROUXD COXIIECTIOXS rtror.rld b: roldered, }{hen I finally did thir, my Biqnrl qained 3 dBr and mv qrotnd svetem had aflly been erposed to the weather g a'nths by thet time. l'lanv peoole use e rEuare of h€avv dutv stainless :teel plete alout ii,r, thidr et the tower base as e central qror.nd point. tie I use |r|t lgr lenqth of tinnrd 3./g. diern. cDgper tubine, bent into a circle ebout the tower baser and Eusoended severel rnctps off the qround to prevent t'e qnnqies. There ere nlrner*rE small hores drilled thru the tubinar and thru eech gcrew is a *6-32 macNne end nutr eech rroroinq iirmly reveret qrou,o wires. The qrotnd wires mav be the near ends of qrowrd radials, or wires to qrotnd rodg rnd old wellsr end to the qrorfid screens. All of my qround wires lre et hest *tf qauqe insulated copper, end cach is terminated in en tninsuleted solder luq. After *verr] solder luqE are mourted Lnder ooe t6-32 screwr the connection is flow ,oldered with r torch (rosin solder pleasel), I have alrnost 900O feet of qrotrtd rrdiits Urii.O, rff rs lonq as my tower heiqhtr end s(xne tD to t00 feet looq. I have r nu.rber of thern tcrmtn.ted in 6 ft. copper-dad qround rods et the far end, I arso have e totel of !60 rquarr feet of qa-Ivanited chicj

feet of thp toner blge, I have rnother t70 or nrore iquere feel $n rrnall 2, r f, pircrsl of gafite qrqnd the m tha further out rloflq the red:ilsr each tied to the nearest rrdiel(s). tn qror-rrd rddition to the 20 rods terminetinq smre of my r..dialsf I have 25 ,rlore 6, - lO. rod5 scattered throuqhout the back yardl each tied to the qrotrnd system. r,ve ds6 tied into my town w.ter pipes svrtem rbout thirtv fret ewev vir a qrourd clenp. I hav? rn old 169, reell deep in mv besemaltr md two oalvenired piges qoinq ell the wav down into the well are dso tied into the qrourd gy5tem, geverd t elso hrve wire fences tied into tle qorrnd'v tYstemr

For qroqtd qrostd radials, rnd svgtem tie-in r*irer I used coerirl crbte rDout the phvrical size of RG-58,/u. r Hat eble to bw I nwber of spmls of this cabte surplus for tl2.0O./100O ft. The insulation quality is still qoodr :nd I sinply rtrip sqne q.rter insuletio.l grherevet to erpose the braid I need to attach a solder h.n, or mat-e sqre connection. Th,e insulation is left on the rernainder of th€ r.hle to protect the breid rqeinst rFids roil rlkaleis ild end abrasim, (I do not use the center condrrtor at ell - the brrid provides emole surf.re erea at RF.)

BASE IXSIILATOR, For the towerq that is! I,m in danaer of repe.tinq whet m.nv euthor: - in lowdown have seid before rne but use the beet qurllty besr lnruletor Ar gossible 06ribla. lonq e section .s also helps. I r.,se a fifteen inch ber tcvlinOricatt of $lid G3 €pory fiberqt.Fs rt the bese of my telescDgioq tower. Abor.rt four inches et each cnd of the bar extcnd into the metal pipe cectims above and beloul leevinq me with e 7 inch erposed sectim of insulator, Coke botiles work es wellr but era r lot ,nore frrqile. D€Dendinq lDcri vour antenne desiqn end efficienryr ttre feedpoint i"pJ-.r *iff be frorn reverd ]rundred thousand to severd rn€qotrns at this Doint, An insulator resistancp of I meqolm rt 180 khr.niqht rob half vor:r RF, A really lousy ingulator crn trke 981 of your RF rnd you'll never know it r{ithout deta,iled neasurements.

DIsttLAToRs in eenerel. Even if vou use nvrm or polypropylene rope for y.xn quy Hires os anteona supportr you rrust still use at least me, prefferably tyror hrqh quality insuletorg nert to the mtennal betrreen the antenna and rope. Theoreticellyl clean fresh nylon plestic rooer or any r@e does not condr.rt at d.c. Howeverr it is far lesi predicetble rt RFt and rfter e few nronths in the weattrer erposed to airborne Ertarninants and pertiduate matterl pickjnq and uD Eorn€ hmiditv as a thin film of witer vagor m it,s surfacel nYlm roger even a sevmty foot lenqthr is qoinq to be a far from qood insutitor. Especidly when we need literally mrny meqohms to preserve the sanctity of our RFI Sor insulate with solid insulatorsl or be sorry. TNs fromdirect erpeiience. ien Comeg, too, has nurprq.r horror stories from correspondents m this topic.

AxrENxA corl. REsrsrANCE. Htxh has been said .bout usinq the hichert Gr1lowest r.sist.ncE coil for the antenna cDil is possible, The icea behind this is iinrote (eee Rich Brutner't ertide gl your rntennes a fe$ months backl, qrormd system resistance and antenna oil resistencp epgear in series with yq,n entenna system resistance. your rnt€nne svstern rcaist.nce - is the mly desirable trler.i.€. the one which rediates, tt is, rnfortrnatelyr in our kinda installations often a tinv fraction of en olm. So it,s th€ rrnallest nunber farl bv end vet it's the one which we,d like to develop rs rr.rh volteqe es gos3ible rrogs. Henr- th€ cDntinued insisteflcE m irprovine qrotnd systernsr rnd l9erhaps...... ere'll se€ the realitv in the nert parrqraph) on buildinq qiqrntic rntenna coils oirt qauqe of larqe litz wirer to kreg th€ RF resistence of qrotnd -o Eil p06sible. rs roh, es 23

ANTEIINA COIIS. L.:t'r qet ro.n p.rtoective m rntmnr cotl nF rciistrntr for r recond. I wm't trlk ln trrmr of Qr which is dire'ctlv rehted but rnre rbstrrEt. 6rrffic! it to ray that the the lower I coils RF resistrne .s oggoied to it'r RF inpedencer the better ttp Q. It's e direct retio, A qrpect coil co.rposed of .botrt 5OO turns of snell eer.ne litt rire on r l/2 inch fiberqlars formr with rbout 7 leverr of tunrr (neled with 'Q' Dolystyrene dopel rrrd $orrt 3' to lt' in lenqth will displey rn RF r"rirtrtra of rbout 38 otrns et 180 kht. If vou ere usina e Bmall sluq of ferrite to ttne the coiL it'i resistance will rise by .bout f0% to 801 to 60 to 78 otvm. lrtrile m thit tolcr do not bc 'O' mirlled by 9rltty mtlr or RF rBittrnc! |tEter r.rdinq! for fcrritr rltnr tn the oil .nd etc....,ttpie testinq devicer rre not puttlnq FOI{ER in rny quuHtY rcorr thr collr rrd mcg vorr put POHE8 .rro3s l hlqh I cirodt end ptrt e pirc of ferritc or irsl gowdg ln itr vq,rr lories qo rky hiqh!!) If you are usinq a lonq sluq of ferrite ln the coil end rmninq a watt or fior€r yrlur coil RF resistance can qo well lbove l@ ohms. The above fiqures assun€ you're keeoinq the coits from dose prorimitv to env metd cabinet rrllsr etc.

The literature shoes that coils vrith lowest RF resistance should heve a larqe diarneterq have only one layer of windinq' and have lenqth end diarneter rouqhlY rqual (i.e, an eiqht inch lonq cnil hround on an eiqht inch form), Ideally qrh a coil would be v'otrid with thick litz wire. Fwthermore, each ediacent windinq should geparated by e smell qaor perheps equal to l/2 lo 3/1 the wire diarneter. (The reonrrnndation for a stn ll inter-wire eaDr end the prohibitim for more than one layer of windinee both rel.te to rddY orrrents snd essocieted lmses, In realitvr these eddy logses ere nowhere near es Droilbitive with litr wirer as when usinq solid wire.) To qet m with our fiQwes, r tinqle laver litr coil woind on r a' diarn, form and about 12' lonq will have rn RF resistene of ebout 15 otrm. A coil wound with larqe lit: oco-tpyina ebor:t l0' on .n I' form will Drobablv end uo rbout l0 otms. A coil on a 12' formr with equil l:nqth rnd dim.r rnd womd with laree litrr nray have a resistince of .bot t 6 otms or better.

Cuttinq cDil resigtance increases the voltaqe across the entenna r€sistancer which is pitifully low to start *ith. But let'E recall that coil r€sist.ncr ii in ierieB hrith around registane?. In many prrts of tlp corrttryr with e few Qror,nd rodsr lnd . doren to twenty 5O'ground radids, and nothinq elser it is possible to qet a orornd sy:tem resist$ce of t0 to 20 ohrns. And with a bit more work' srJch as nx)re rods and som€ ScreEninq l[|d tmre radials' it is entirely possible to qet a qround resistence of 5-6 olms without backbreakjnq effort' In many ptrts of the lower Eastern seaboerdr lrtd ln parts of ttn Southwestr indudinq much of New Merimr as rrEll aE in prrts of Cdilorniar sudr qround resistances as mentioned above rre ersily rttrined.

On the other handl in larqe perts of New Enqland rnd New York gteter ri wsll rt portions of Californier (end many other parti of the cDtrttry which I'm too iqnorutt to loow eboutll tha soil condwtivity is terribler end th€ soil y"ry rocky rs uell. [.o]r water teble often aqqravates the situetim.) I described my qrourd lystem e few Dereqrrphs ebove. If enythinor the description was on the cdnservative Eide - my qrornd gy:tern could easily be c'lled overkjll for e typical arnateur installation. Xonethelessi my ,n€asurd qrorfid resistance varies from 140 to 290 olmsr dependinq upon the w€tn"sg of the qrourdr €tc. This is not an error or fluke of measurement. Rich Brmner in HessectilJss"tts uses a sliqhtly less sophisticated qrotnd svetemf and hie qrould resistrnce falls in tha serne ranqe. Hhen Dick Hilferty lived in Lonq Islandr the picture wrE even wor:e! Apparently ilim Hhite in New Harnpshire faces an even rorse groblem sith qround rrsistrnce. On the other hand' Dich Hilferty now tives in New llericor and with e reletively sinple qrourd 24 I

rystemt hi: qrourd resistrnce {RF) is down .ro$td tO otms.

If your qround resistrnce fairly is low, tike belos 35 olmsr it obviotrslv Days to eo berserk etld tp€nd sorne time aettinq the last bit of efficiency orrt of ydrr anteflne coilr on th other hardr if your eround resist-ce hovers arorrrd t50 - r90 otms, ctnnq ten or twenty otuns off vour coil resistence is not even me decibel in qain, Even brnqina r 30 olm coil re6istance (easilv atteineble with even | flrodest effort in e compact coill doh,n to I olm uttFossible anvwey for envone withotrt cryoaenics) wor.rld not yield anv rDpreciable irprovernent in siqnal strenqth. I ern not sayinq you would want to be happv with e very tiny coil tuned by e ferrite your sluq for hiqh gerformance Lowfer beacon'in an erea of lousy soil condtrtivityr Gt's resistance could easily be t40 olrns or rnore) but on the other hand be realistic in your efforts. It,s hardly worth th€ ergense and ef{ort of buildinq a 10" dietn. single layer coil wor-nd with heavy litr to qet you, coil resistance from Zg ohrns down to l0 ot''s in a svstem your where erotnd registance is ebove ro0 ohms, B€tter tg spend the effort on improvino your erornd syste,n. I would srnqesi. i"rq;fot about 30 olms for DeoDle with lousv (easily soil conductivity attainable with lit: :nd a sma1l, lik-e l/2 dian't 6 laver coil perhaps with a tinv piece of ferrite sluq for fine peakinq,) on ttre other hand' if votr qround resi=tilce is t0 to 25 otmsr or a bit fin,r€r eo rll or,t, and hrind a 7" or 12" diarneter sinqle laver corl with heavv litr,

Now to ferrite for a minute. I hate ferrite for hioh Z (irnoedance)power aoplications st'ch e5 this. At any kind of power and hiqh inpedance levelE, ferrite or iron oolroer saturates immediately. gofne This converts of your poh,er to heat in the corel and brorse yetr Gn my book..,..) creates a nastv amotnt of harmonrc enerqy bv it,s cliDpina actisl, Of cotrrser this lost enerey translates into hiqher coil RF resistance. I much prefir tr,ninq mv l75o finals with m'rrtiple tags m the hiqh end of the antenna coilr and inen-rine tminq with e 50 or 160 pf hiqh vottage veriable capacitor lthe arnateur transmittinq type - make gure insulatim is cpramicr qlass), Dorc€lain or Altho the ctg:.itor will introdue a certain emowt of cirorratinq current which can't help but lose a bit "t p;;;;; this hiqh irpecancer in oractice tuinq capacitors work a mirion. times betier than atriustable ferrite (uqh!) cores, Don't try usinq more than about 2oo or 2g0 pf capacitance. (you cAN qet awev with more if your antenna has a v€rv biq tophatr and therefore has itgelf a larqe ctpacitence to around.) you WILL qet start to incyeasinq losses at some point. One rnore nice thinq abotrt capacitors for - tminq not only don't they provide envthinq to Baturate rrtd qenerate harrmnics, their very addition to to a hiAh-Z final circuit like this (in my erperieflcP) seems to sionificanily drop the ernomt of harmonic enerqy radiated by the system as ogDosed to ttninq only bv adiustable coil taps, Of cor.rsel th€re ie an erplanatiori for this, The smalr anromt of a.ddedcepeotv provides a new RF cirarit at the hiqher frequenciesr whereag before the harnro.ie enerqy had oflly to look at the cagacitencF of the tower to qror.'d. This new tmed circuit seems to be especia'v effective at reducinq the nunter and eneroy cootent of harmonics. On my antenna Eystem, rnythiha over abo.rt 50 pf of added relacity qror.nd to has this very desirabte pffect. I now use caDacitence ttnine erdusively.

I ern not totallv aqianst ferrite powder or iran rqds, Esoeoally for an ingtalation that ttust be omoact or YerY inerpensive or coostructed with minimum tiare end effort, a ernount small of ferrite in th€ anteflna coil will not hwt matters .il.lch.

For power ciro.tits at lower inpedancesr strh as the drain tank coil of a VI{OS FET khar. impedance 30 to 100 ofms) ferrite or iron gowder tminq is actually e boori, and very tlesirrble. My olrrent VMOS final ernp rr6es a multi-tapped tilk coil of 50 turns enanelled 25

rire wo.nd on rT106-3 f ftf-'r oowder toroid core, ud it ir hiohlv rfficient. I heve etso used snall tltq tlrtrd coil forrns pith qood srrccpss for ttre tenk coil, Mrke rurr yq,r 'rluq' lr r€rtly I oood frrrltc or lrm goLd€r for thia frrqrrncy - qrr rrf thore m.rnrtd or bt$t rlLcs wlll r.rllv rlgr qlt yqn drodtl!

TOP LOADIIG COIIS. For v€lrir firrh of the rdio rrnateur litrreture devoted to electricallv thort verti.Al trensmittinq antennrs has prornllqeted the idee thet e chort vertical crn be mede r more efficient rediator bv 'lenqtheninq' it by rddinq r enter loadinq

I can surn up the reectim of almost everyme who has tried the tectniqc by Daraphrasine Gary l{eldsmith..,.,.'it dopsn't work worth a darn.....th€ loadlnq coilr tlp it': srDposed to ele'ctriarly lenqthen tip vertical radiatorr ertually seems to rct likp some kind of a hiah 0 choke' isoletinq th€ radiator (or cepacjtv hat) ebove the indwtor end discmnectinq it." I would not€ in this respectr before the tertbook peool: strrt' screarninq (end h€aven hnows I myself use tertbooks a lot - witness my sophiiticated transrnittina stationlr that no less an authority than M. F. (Douqf DeXewr of ARRL/OST Tectnical dept. famer and en ercellent RF enqineer in his own riqhtr h|r made thr rerne observetion in several of his 9!,blications. He admitr thet there rre tlE theorip: end charts m th€ on€ handr but th€re is th: hard data oo the other hand!... He rnekcs cte interestinq point. Some of these center or top-loadinq (coill srfiquretimt do srcm to increase local field strenqthr out to hndreds of yrrds or even e mile or txo, but no me has ever been eble to doo.rnent the sliqhtest inprovement b€yond thp horirm m lcrqwrver up thru 160 meters, These cliticisns do not necesserily hold truc for verticels $praochinq a decent fraction of a wavelenqth. Rrt for ygTllrell thet rn r tiny fractim of a wavelenqth in heiqhtr thev ere perfectly velid. Douq Dernaw dso points nrt the incredible nunber of Amateur Radio and conmercial radio engineerinc prSlicrtimc rnd tcrts in which th€se dairns have rpDeared, despite lack of real prmf, l,d rlvr if you,rr considerinq addinq I loadinq coil in the vertic.lr spend the enerqy to put u9 r decent tophat instead. It worksl Gery Haldsmith spent rnost of the sprinq (and there rrere rnny before him!! tryinq many verietions on the loadinq coil therne with no tucclrtr

The above critique wls not intended to condemn ell methods of'bnqtheninq' ghort verticals. tlrrh of the rtnateur and erDerirnenter literature seems to thow thet I mor? 'L' distributed or inductance cill mak€ | differencel r positive me, in rrdietion efficiency. Ttrrsl a vertical which is not a solidr linear wire or piper but e qentle:piral 26

reems fairly effective en improvement over an uraided vertical. &.lch an enterine is often celled a h€licd verticalr helical or .ntenna, Th€re .re '€verar other takeoff' m this tlEm€ that are feirlv effectiver too. Tears aqo Ken comell pr.blished "o.r*-1trrr * tr,i, in his columr mostlv reqerdinq so,Tr€ work done by Keith ol:sr m the Hesi ceost yith mod€ls m 16Onreters.

FoLrlED vEnrrcAls AttD'FoLDm xoNoFoLEs.. rn a word, these desiqns have been prsoFed several tirps es ettractive, more efficjent alternatives to baie fed short vcrticils. Ttp drim qoes that (white i.Et as phvsicalv ;hort) the addition of tmed or loaded downleads to the (and vertical ctranqinq feedpoint tectniaue.nd imDedance) will very qains qrventional Yield nice over short verti.rl5. Aqain, this lrene is for verticals below l/f wavelenqth in heieht. Aqainr the cleims sorJr|d qreat, And y.'t, can find rny nur$er of literature rnd tert references which inplv that strch a system *ill heve qreater radiitim resistence for it,s (that,s. qoodie - sirel it rneans you rediate,nore!) and lower feedpoint losses Oower imped.nce, so Et_rpDosedlyrnrch less inductance needec, to metch iltenni gap:ritane to qrotnd - and therefore lower resistancp end maqnetic losses in the bese loadinq coil....or so qoes...!. the storv Thats the chim.... Now for the realitv. The tl=orv seems to work for Qreat v€rti-rs that rre som€what rhorter than r l/4 savelenEthr rnd gerheDs even l./g ravelenqth or less, B.lt there i: sorne indetermined sosEover point at which other losses and other consideretims begin to predo.ninrt€. It i.Et doesn't work for verticals that are r/r00 or r/s0 th or less of a ravelenqth (rnd retriember5o'at l75o npters is less thrn l,/oo th wavelenethll in heiqht. As a matter of factr r have never for..d anvone with hardcore ergerience (ic, who t""uv iii"o i*l who wes able to qet rnv such enboditnent to radiate anyrrhere near ls well as a basefed short yertiralr I myself spent h-ndreds of hotrs in the sprinqtime tryinq "r"rv-.*oi"att" veriatim to the folded monopole idea. The best sinqle embodirneot i*ni.rt ".r ridiorlously convoluted end cornplet and involved one dolen downleads m a SO, t";; _ fed in e ttrtnq€ sytldlronYt was lt dB below a conventimal base insulated vertical of the 6arne heiqht in both locel end l0oo areter and I mile and 5 mile field strenqth tests (for the srtrE transmitter oower output). quess uv best is that I spent well over 3oo hotrrs otr trris (Ite Droiectr and I have a decent backqror-rrd in elestrical enqineerinqr antenna desiqn, ind low frequency RF hlso microwave - antenne desiqn frorn years aqo). I elso enioyed freqrpnt looq-distance qrsultations teleohone wiih antenna erperts durinq this period _ to no eveil. Garv Haldsrnith in California ajso spent at least the sarne rrmLnt of time this cprinq independently pursuinq the sarne cogrse of erperimentation. (lfe corrpared notes mly toward the end of our work.) Gary,s erDertencps seern to duplicete mine. I have sine learned fron Ken Cornell rnd Dick Hilferty that this ide; ha;-l; tried by reverd other rowfers end erperimenters in the 9a5t, (rll individuars hrith .n ercErlmt baEkr|rqr|d in the ghysicel rnd enqinperinq tcieoc!5,, as well as in the low frequencies), md no one has been abre to csne w with r workabre embodirnent, The best enswer saerns to be thet the nrodels falr apart wlpn the short verticar is less than sdn€thinq (irst .n edlEeted quess!) m the order o€ r/3o th of e wevelenqth in treiqht. r ; not sryinq gositivelv that it can,t rork. I believe that nrost breakthrotnhs are rnade by iqnorinq idee that so.nethino the is inuossible. However; nxr€h .s I rike to believe in ihe-impossibre, or rt_leest dlow es it miqht eristr Lrust edmit that I arn totally burned out o.l t*s idee. And I srsider mvEelf r feirlv creative end imaqinetiv" p"rs*..,.- i"r.ll-rr", therer... rnd eood lr-Ek!

I r.'id likr to ecknowledqe the h€lp of :everel individuals. I elso reilize that e nurter of points r have made here were made before in this pr.6riciti*r. rn"v ar" lprcverr thrt geinfully Oointr I vpry leerned or re-learned frofi my own erperieotr _ grd 27

tley ere trrteinly rrorth regertinq! XV thrnks to Todd Robertsr Rich Brrnnrrr Dick Hilfcrtvr Ken Cororll, Gery t{eldsmith, t{.tt Glrrar, C1p HossfietO,-iifi X*iiir*. xio.r,, .tld Ftenk Holfqre.m for dissrBioos, correBpo.rd€ocer eid rnd inriqtrti in mi rrpcrirncntr sith rntennrs &d qroirrdr orly tNs rrxnflrer.

TUIED COUNTERPOTSE by K.ith Ollon In lotng bsck ovc. thc lonEr.vc lit.rstu.a alnc. th. turn of th. c.nluryr l! It rpPrr.nt tli.t afi.a rnlanna tunint t.a ua.d foa both tr.ngait .nd .ac.ivc. lly loat aucc.laful taall uaa par.l tcl tun.d cl.cqi!a tn thc fin.l t.nkr tith I F...d.y ahi.ld.d ttnk rnd v.Fior.to. tsncd rntlnn.. Th. Fsrsd.y ahi.ld cr^ b. conttruct.d by traPPina th. t.nk rlth about 1 l./4 turn of thl! b..aa or coPp.r. Tha lrdk corl rhould bc rr.pp.d rith . tood trada of o.&brlc o. oth.r lnlulatln! t.p.. In.ul.i. th. .nd of th. FaFrd.y thr.ld ti!h . g.rticrl ttrlP ot doubl. tidcd taPar auch .t o.rP.t l.yar'a t.p. ao aa to prcvcnt iha fhta fro. batn! r rhoatad tuan. C.ound th. -..htD b[r.. On lolcnold!' th. plokup ltak o.n b. t.pP.d to e..y th. coupltnt or rount lt on. !ctt.bl. fo.r.nd.ltd. lt up .nd dorn th. coil. tith to.olda' . t.pp.d rooondfy ttll h.v. to do. I a..a to lct th. bcat r.aultr rlth a tun.d countaapoia.. Tho null potnt of !h. lrnk tr lrosnd.d. Thlr ahould b. .t c. dcrr tha o.nt.r of th. plckup ltnk. To tun., r.aon.t. th. antcnna aaainat th. aull Polni a.ound. -Thcn roloart. th. ooqntr.poit..lalnrt th. null Potntt ttth th. .ntonn. .nd loadlall d.vlc. dlaconn.ct.d. Tun. for a.xitu currant ln tha ant.nnt rnd llnltsa curaan! ln ih. laad fnoa tha null polnt io around. Tha covntarpolaa lhoqld b. a.v.a.l t1..4 rnd, tf poattbla' all rl.aa ahould b. th. a&. l.nath and .pprorlaatcly e to €l f..t off th. troudd. ?FS uror,a rl..a 160 f.ct lont r.r.ntcd In . f.n ov.. rn a.c of 45 d.ar..a. I lntand ' to bqtld thr.. of th.a. count.apolaa aaac.bll.a, and ua. th.. rapr..t.ly o. to8ath.. to !.. lf tt rtll lhor rny dtr.ottet.ly. It l. v.ry difticult to ..tch th. lround .nd oil . aho.t ant.nn. to th. hot and of r prrrllot tun.d trak olaoutt unl.aa th. ant.nn. lt a hrlf tava.

(Ed. llot.- ColP.rilona bctta.n thla count.rPoia. lat up and aarth lround thorcd quii. dtff...nt .a!ul!l for aroundt.v. .nd akF.v.. ) 2B

I{OTESON ADJUSTING I75OMETER

TRANSMITUNG ANTEXNAS

KEYIIORDS!Antenna' trensmittingr verticdr looDrpolariretionr

field strenqth, measurernentsrrernote measurernentslcouplinq. O trrr bv Vincent J. Pinto I I h"u" discovered that thinqs are not alway: straiqhtforward and simgle wh€n makino adiustments o5 a 1750 meter transmittinq antenna via field strenqth measwements, There adFar to be severd anomalies and errors introdwed into certain such Eituations due to the ertremelv short electrical heiqht (in terms of a wavelenqth) of the transmittinq antenna, There may be other factors involvedr toor such eE inductive utd / or capacitive couplinq of the various Dhvsicel devices involved, as well as less than omptimal eround systems in many amateur installations, Unintentional horirontallv polarired radietion can also confuse the measurement picture. I am not the only person to have noted {and been stymied by...) these anomaliesl thcre are several other Lowfers who have reoorted the same type of problem, Amonq others' I recently heard of experiences similar to mine from lI.P. 'Buddy" Horqan in Floridar who had to improvise to find a satisfactory way of measurinq field strenath, This artide will attempt to outline some of the myths and fallacies of adiustinq transmittinq antennas on this bandr as well as erplore some satisfactory ways to measure relative field strenqth, For some of the problem areasr there are no outrieht answers, but some eeneral Drecautions and caveats that we can talk about. We will firet look at commonly used Lowfer transmittina antennagr and then rt meaEurementoroblems,

Let's first define the field. He'll summarize the desirable properties of any short (i,e,l Part 15 cornpatible) transmittinq antenna for the 1750 meter band. Th€ follor"rinq disctrssims assurne electricallv Ehort utennag at low frequencies rrrh rs th€ l75O meter band. Thereforel the words low frequency or clectrically clprt miy not rlnays rppear in the tert - they are as5uned.

Firstl the antenna should be verticallv polarited. There is no place in the arene of very short low frequency antennas dose to the qround (in terms of a wavelenqth) for horirontal polariration. Althouqh such antennas miaht show imgressive near-field field strenqths due to capacitive or inductrve couplinq, the field strenqth falls off rapidly at any distance, The horizontal component tends.to erperiencB qreat absorption and loss from nearby obstades and eround surface irreqularitieE, If you can qet a horirontd low frequency antenna lonq enouqh (at least a aood fraction of e wevelenqth) and hiqh enouqh (this ofle can be fudqed if there lre no nearby obstades or terrain featuresl and positioned over a qood qround plane (such rs a lake or swarnplr then yor.l can realire feir field strenqth at a distance. Howeverl such an antenn. would not conform with FCC Part l5 requirements (due to lenoth) urless vor.rwere to rm reduc€d power. In eeneralr horirontal cornponents from a very short low freqtrcncv radiator tend to erperience ercessive absorotion in the near field from nearby obiects end obstades. So the answer lies in makinq sure you radiate vertically polarired rn€reyr

There are several commonly used confieurations for this. lile can use a base-fed verticel radiator. Or we can use a vertical radiator with a tophat, The tophat nrev be horizontal or may be slopine as in an urnbrella confiquration. When vertical radirtor5 29

ere electricalty shortr the efficiency depends to e qreat ertent upon the efficiencv of the qrotnd plane. tn most areasr th€ 6oil elone will be nowhere near sufficientr and in eddition to qround rodsr an artificiel Qround plane must be used. The rnost conmon roproach is to use radid wiresr ebovel on1 or in the soil to inprove the qrowld. ThP rule with rrdials iE the more the merrierr tnd each should be et least as lonq es the verticil is hiqh. A quarter wevelenqth to half wavelenath per radial i5 much betterr but most of us cannot afford anywhere near that, Another method somewhat better than discrete rrdiels iE to install a Qround screen o,f metallic mesh rt qrowld level or a fiw feet above it for at least a5 far a5 the tower is hiqh, Some prectical installatims use some rcreen on the qrotnd near th€ tower with radials takjnq w the iob bevond ten or twenty fcet.

The radiation from a vertical ho tophat) will be purelv verticd golarizationt end the illtenna becomes a Dure E-field device. Wlpn you add a small sYnmetrical tophatr the radiation remains totallv vertical' with E-field mode predorninatino. Since the radiation resistance will be a verv small numberr the qreatest amount of antenna orrrent will be dissioated in the necessarily qreater reEistance of the entire qtound system. Nearby obstades above the qround plane can rbsorb and dissipate an eooreciable amount of near E-field enerqvr so foliaqe and bulidinqs can steal some gohrerr Althouqh a tophat can increase the radiation resistance and effective electrical heiqht of a vertical' there are confoundina factors, The tophat gvstetn becomes a qilnt ceDaEitor plate with respetrt to qrornd (the other 'plate")' Resistive obstades between the two 'pletes", such aE foliaqe and buildinqs will now have a qreater n€qative effect m the oicture. Thev will contribute rnore heavily to E-field losses, 5or if your tophat vertical is in en area h,ith no obstades and veeetationr lnd an ercellent qround svgtemr the tophat ir r reel plus. A tophat is still a plus in a setup where there are foliaqe rrld buildinqgr etcf present' or wh€rE the qround is less than perfect (as in the real wortd of hobbyist communicationslr but some of it'5 aains will be offset bY increased absorptive losses frorn obstades in the 'capacitor" area. A poor Qround is a.lso another loss factor. A oerfect qround would have no resistancer and would simulate a lerqe flat m€tal Delte beneath the antenna. In the real worldr with perhaps thirty radial wires on oooY rockv soitr the qround acquires a certain depth into the soil, The nqround" soil ie not a Derfect conductor and the effective seen by the E-field indudes a lot of losses from the Doorly conductiver absorptive soil. So the ideal vertical should Hork over r oerfest qtound.

Let's talk about tophats for a minute. The ideal tophat is one that makes e fiqure T end extends in two or more directions. A less efficient verEionr but economicalr [J5P53 fiqure L arranqement - iust one tophat wire in one direction. Ideally the best tophat for a short vertical should be a bit less in radiue than the lenqth of the vertical Dortioo, In realityr especially with very short antennasr even tophats well lonqer in redius than tower heiqht often seem to do verv well. Ideallv' the tophat ghould be comgosed of a number of radial wires or sgokesr extendinq in different directionE. fobably a qood practical fieure for Lowfer installations is 1O to 15 rrdial spkoes. Idedly the radials will be evenly distributed over all points of the compass.

lf there is only one tophat spoke (an L - in one direction)r or if the toghat wites are loosided - that isr mncentrated toward one directionr then a siqnificant amount of horirontal radiation will take Dlace. Altho the'tophat mav still afford some benefit over a hatless v€tticalr it's enhancement will be reduced bv the introdtrtion of the horirontallv Dolarited enerey. In manv practical Lowfer installations with tophatet there is Eorne horirontal radiation from the tophat. 30 I

There is another wrv of orodudnq r verticdly golarit€d wave. Yot cen cr:ct e lo@ $tenna. The plane of the toop is verticd - perpendia;l:r to the qror.nd. Ttr rrdirtion from an electrically tmall loop is purely H-field, lt is alrnost owely vertically golarired comgonent if the shape factor is qood' Two thinqs to look rt hcre. tf the rhape is not qood - not e gerfect 3quare or ciranlar loop - then therc will be tonre horirontal mmponents, Generallvr as lonq as tlte thinq lookE rotqhly circuler or rowhly Equere, the radiation wlll be vertically polerired for all prarticel purgores. As lmq as the loop remains a small fraction of a wavelenqth in totel lenqthr thc rrdietion is pure H-field. If the loop approaches an eppreciable part of a wavelenqth in lenqthr there will be increasinq E-field radiationr rnd increasinq components (et certain lenqths) that will be horirontally polarired. The neat thinq .bout the H-field ir that it totally iqnores nearby lossy or resistive obstacles. Due to the abgenc: of E-field moder th€re is no loss from goor qround either, The H-field radiator is besicallv oblivious to the qromd planer and anv inefficiencies attendant' So you do not even need a around system et ell, The H-field device is totally obliviouB to moisture and Ireather chanqes on nearby obiects' too. About the only thinq that could affect it would be a nearbyr dosely coupled loop. This H-field feature can make th€ loop an ettractive .ntenna for an installation in an area of Door soil conductivitv and / gr loti of terrrin rnd folieoe obstades.

For 1750 meter Lowfer workr the loop would ideally be at least 30 to 40 feet on a side. However the phvsical wire lenqth of such a loog would be over 15 metersr end miEht possiblv fell afoul of Part t5. Another way of interpretinq Part lS's requirernent mioht be to calculate theoretically the si:e loop needed to oroduce th€ rarne field strenqth as a 15 meter vertical over qood eroundr end qo with that Eire loop. The necessarv fiqures are in anv qood radio enqineerine handbook, Some peopler toor interoret Part 15 as reelly indudinq a volume of t5 metersr and not iust a lined lenqth. The FCC has qiven conflictinq and confusinq interpretations to this l5 fiEter thinq when DreEented with qr.pries by erperimenterE. It is likelv they rre every bit as mnfused as hrp rr€r Whetever interpretation you decide it is fittina to qo hrith' heep your radiated sianal Etable and dean frotn env harmonics or EDUrsl end it iB unlikely you will hear further about the mattter. In any cager it has been proven that a loop that can be easily built by the averaqe Lowferr canl in areas of poor soil conductivity and / or lots of obstadesr easily surpass the gerforrnance of the best cmventional vertical antenna. I would like to thank Dick.Hilferty for nakinq me.wtre of loops es a Dractical alternetiver rnd for a terrific srnoult of lnformatim m th€ us? md Drogertie! of loopg on lonqwaver

The loop radiator will not fiqure much in the followine disorssions on field strenqth measurement, Loops are not in commonuser their vaqaries are fewer end Bimpler grhen it comes to field strenqth measurementl and th€y are not subiect to the many confiourations and ills that a vertical radiator mioht exoerience.

?Ihen I first put a beacon on the airr I used a passive field strenqth meter loceted near the vertical tower (about 22 feet awayl to check chanqes in field :trenqth dtn to power and transmitter adiustments, tuninq th€ find couplinq coilr and desiqn Ehanqesin the toh,er and tophat. Erperience has shown that as lonq as your qrotnd Eystem is fairlv adequate ( - lotE of radials or screeninq)' this m€thod works fine for dooJmentinq chanqes due to transmitter adfustnent:1 gower clwrqes rnd final loadinq coil hninq, In other wordsr relative chanqes on your rneter will reflect true chanqee in vour field strenqth that scrmeoneat a digtance (over the horizonl would see, }le are assuminq that vour final amplifier is located at the base of the towerr and that the cables carryinq RF drive and d.c power to it are well qrounded and shielded. (Radiation JI

from these lines can play havoc with your measurernents at any staqe - so this tvoe of interaction rrust be culled out.) Bv the same tokenr the field strenqth meter cannot be located in your shack eitherr urtless your driver staees are well shielded and well erounded. Another buqaboo to the above formula would ocrur if vou had a very poor qror.nd system' Then every obiect in the near field takes on a life of it's own in a s€rispr ind even small movernents of your body or hand (or a tool) can prcrduceerossr rrrealistic chanqee on your field strenqth meter. As lono as vou had a fair oround Evstem to beqin withr a nearby (5 to 35 feet from tower) nreter will also reflect fairly accurately chanqes in your qround system, such as improvements or addition of more radials, Aeainr a relative increage on the rneter will corresoond to an increase at a eood distance,

You'll notice I specifically left out antenna adiustments and toohat adiustments as thinqs that can accurately be rnonitored lrith the nearby freld strenqth meter. ThBre is a reason for that, Readinas from the fii€ter in response to such adlustments can be very misleadinq, In any real installation, there will be too muchRF from the .wrono,, sources coupled to the field strenqth mmeter to provide accr-rratereadinqs realtive to true chanqe in field strenoth at a distance. Some of the confosrdino factors are 'loops,'r horirontal radiation componentg, qround field uneven qround currents, and electrostatic and inductive couplinq to the radiator and toohat elements, tn manv cases it is possible to record a very nice local (nearbv fietd Etrenath rnetert inprovement due to an antenna./tophat chanqe, onlv to discover that the power at a distance actually decreased. Bear in mind that anv chanqe to the antenna or it's tmhat (or to obstacles nearbvr srrch .s nrovinq them will result in a distortion of the terrifically comDlex fields local to the radiatorr with often nrisleadinq results recorded on nearbv equipment)

ThuE you can make a chanee in tower heiqht, or in size of toohatr or number of tophat wires {or in slope anqle of umbrella toohat h,ire6,or lenqth of tophat, ,...andso on} and can onlv erpect a totally misleadinq readinq from a nearby field Etrenqth meter, So1do we eo out and build a small amplifred field strenqth meterl and place it 100 yards awayr usinq that for our readinqs? The answer is nor and for the Eame reasons that invalidated a meter at 5 to 50 feet. Even at 100 vards there are still olenty of stray fields and couolinq effectE that do not accuratelv reflect a true power chanqe at a distance, So now we qet in the car and try uginq a tunable voltmeter or receiver at a half mile or one mile distance, It's still no goodl rhe readrnqs can still be totalty erroneous, Like a meter near the towerl the meter/receiver at a mile or half mile will accuratelv reFlect chanoes in actua] transmitter power or deEiqnr tuninq the final coilr or improvementsin the eround system (like addinq more radials and lowerinq qround "stranqe" resistance)r but there are still too many factors influencinq the readinq to make it useful for monitorinq chanq€s to the antenna or tophat, The only thinq that,s chanqed as compared to more nearby meter positions is the tyoe of error. At anv "stranee" distance like a miler freak effects due to qround cttrrent flow become less siqniqicant. Same is true for caoacitive couolinq to antenna elements, llhat reallv gredominates at these distances to rness up readines is the comDonentof horizontal radiation and some distortions of the antenna's,pattern in the near field. Althouoh horilontal radiation mav make vour antenna look better at a miler that radiation will never make it to a receivinq site 40 miles away.

Nor are we really safe even at 3 or 4 miles, Effects due to horirontal radiation and freak field shape effects can still Dredominate, Another thinq to beware of when makinq rneasurementE with a receiver within the first five or so miles is power line cor+linq, If your immediate neiqhborhood is filled with power linesr and especially if

l\._ 32

you have some form your of toohat on $tennr, you csn colph r riqnificent rmqfit of ytrur power power into the lines. Nowr this qets rerediated'mainlv in the neiqhborhood of tha power lines for the first few miles, This can Froduc€ hiqhly arnrinq resurts. rn one cese' the addition of a lonq L tophet to r tower thet previously had Lnly r ihort lotnd toohat yielded qain e 20 dB in power on a neerby €S feet' eieiO strenqitr r:ter, rnd an impressive 26 dB qain at me mlle rweyr A receivpr at I miler f,eclrded en improvement of 4 dB, The varmint responsible for the reedinq tn tne Ldt vero was sirnple electrostatic co,prinq between the meter antenna and tL n"irtv t"ptt"t *ir", (A vastly increased local E-Field did not help matters.) The olprit in the one fiUle readinq was couplinq from the tophat to a nearby power liner which reredieted the siqnal to nearbv obiects. The biqqest sinqle nrlprit et the ,l mile point *i, aoparentrv the increased arnount of horizontar rediation. rt never made it .nrh beyind tL l mite mrrkr es we'll see in partinrlar a mornent. This chanqe detailed above pioau."O afrrrort no effect aE measured at a distance of 40 milesr and a Eliqht neaativ€ effect rt 75 miles. So we see that local measurements can be very misleadinq.

lly own erDerience has shown that raadinqs h,ithin the first ten miles ere elwayi suspect when recordinq chanqes in field strenqth due to antenna or tophat chanqes, obviouslvr as you eet even nearerr it qets worse. some of these measurement errors would not ocanr if we were not usine antennas that are sr,rch a tiny friction of e navelenqth in electrical heiqht.

If you have to do near measurementsl fust remember that th€ farther the better. So 3 miles will usuarly be somewhat fi)ore acorrate than a point 200 yards.,""y. B,rt th" only sure method iE to spt up a repeatable observation point with a rec€iver at well over ten miles (or bevond,,,....). jo In any casepif you must co.rpro,nise arrO iom. worx with a meter in the yardr at the very least keep the nreter away from power linesr ind out beyond the cirde defined by the tophat. This will help somer but;;t; *tot" tot. Individual cases do have you individual merits. may find that in your tltuation one-half mile is perfectly adequate for monitorinq rnost chanqes to th€ eltennr. Eut i.rst beware those misteadinq readinoe.

l{v experience has shown that the only really reliable field strenqth results come from beyond 35 to 40 miles. Now, at forty miles, as at 2 miles, we are no lonqer talkrlnq about usina a simple amolified field strenath meter. HFasurements (aronatc rnd repeatable relative meaEurements) et these distances must use a qoodl selective, stable tunable receiver or tunable RF voltmeter. The monitor receiver antenna a?rrst vertically polarired be and be totaly nondirectional. I flnd atwo ana "1Jil*i-portrtf" active whip to be the perfect fierd strenqth antenna for my reeiver, iiv* h"pp"n to have a Lowfer friend at thirty five or forty miles or more |rith I very sensiHve, 'rartowl tnetered receiverl end a suitable antennal you can use him/her es your renrote field strenqth meter, Mv ideas for a iuitable anienna at votrr buddv,r ho,se hrorJrdbr an outdoor fired active whior or a larqe Oike 4 foot diarn,l.fired outdoor looo. Even if vour dista't measurernents and comparisons are made over r geriod of dryr and weeksl and your br.ddv does not heve the best s-meter in tl* ;;;il;;oo will probably still be a hundred tirnes better off than if yq.r use a local rn€ter to measure antenna chanqes, You will eventually learn to cornpensate for differences in readinq6 due to outside factors such as recent rainfell (soaks th€ qrot'd over the path yietdinq stronqer siqnals! or dav to dav yor.r,lt chanqes in the receiver. stil! be e t-oi ueiter oer than tryinq to fiqure out why your backverd meter reeds a *rrusandfolO frmio"**nt in siqnal strenqth from lowerinq your tower to half heiqhflll JJ

To record and doonrent antenna nrodificetions I rnade in the sprinq of 1983r I qot in ttp h.bit of brinqinq my receiver and r portible ective whip to vork with me alnpst every dav. t made a map of several points alonq roads near hrork at 23r 37 and 42 miles resoectively fronr my tower, I th€n started keepinq deteiled dailv records of field rtrEnath at each point. As I erperimented with tower erld tophatr I correleted thege reeults with reports from Lowfers at 73 miles Ea5t and 7O miles South. I must cmfess that I sonptimes r.ur uD enormous phone bills to BiIl Murr at 70 miles south in New Jer:ev, but I was able to sucessfullY cornplete mY antenna erperiments and qet gredictable results. The difference between near field and distant measurements in B(me of these erperiments v,las truly ama:inqr and I learned a very imoortent lesson fro,m it.

.l

VPAntenna, l98S 18oo }IETSR FIEI,D ST?ENGTE }1IASURq,IEN:S Rlcherd G. Brnancr

LOITIERS (Ior Frcqucncy Rrdl,o E-!€!lacute!3) operating 1n the 160 to l,9O ldz brBd urd.t Prlt 15 of tb. FCC Rulcc aad R.8llatloar (1) rrc rcutaly arrra of tbr eltcraatltaa lor oPatatlon:

I Fl.lal .tr.agth .t ,Oo o.te!8 oC z4o0/t:rdl|. olcrovolta per Eatc!. 2. O!. rrtt laput ald 15 ectcr altcnnt PluE f6ed11n. Ietrgth.

tAl sorr rdtsBtrgaous altcraetlrr l'! lot obtlous, end tecclt rcquleltioa of ra llt-1o9/I'trl!t'89 fl.ld rt!.agth E.te! grt. E. th. opporturdtt to ccttk tbr qucatloa. For ggiilancr I rurrrycd th. m11eb1o 11t.te!u8c oa fla1d st!.!gtb celculetloaa, then Etd. crlcnlrtloac .!rl tasts rt l5o lt8z for coopr!1roE.

nl.ld sts.lFtb Fomulec A rurr.y o! the ll'tcraturo produced nlay flelil rtr.!8th foraulea' el1 aarulrJ.ag ea iaflaltcly coaductlnli grouad vhlcb iE colt aacuradly aot tb. !.rl ro!1,d. lba .tfoct of loacea 1a the .a!tb' uPotr tb. sultrcc rr?.r d.pcad! h ! r6htltely cocpl'lcated try uPon th. f!.quclcyr dfulectria coBstaat' thc coailuctivl'ty ot th. aerth, aad th. lctulI dLrtrqc.. ltc cffact of thc catth loscas Lr not nc5llgC'bler rs tc rI11 cec. Actu.l Ec.rulco.lta E.y bc balf those celculet?d fro! tha l,lfhite colductl.o! fortrufrg.

( tbc Eoat coayadaEt forrulaa I f ouail rlre lroa !::::::::::::::::lilaoaanil Eornuag. 2)

(e) Elr,./t - Prettc 587o A:L IC A

Rccelved slg'tal 18 lrlcroyolts per Eete! rt/8 D .. : Dlrtlltc. 1s Ej.lcs lro8 trrasaittca to t.ccive! BI'I Pratta = Porer lD rrtts g!!i!g! bJr th. r!teB!!

1.25Ithc (b) E , r ----?:- Pf/a

E _ t = Rrcelrcd si8pal la ElcroyoltB !e! Ert.! N/tt I' = l!t.!Ea cqrlcnt la rapcrcc b. . Effrctivc hcl,gbt of th. altcare h E.trr! d g D16trBc. frolt tb. Idlatla8 cyatrn 1n ldloaetete f r Froqucacy 1n kl.lob.ltz

34 Sccoail cllolcc 1c froa Rcf.raacr Dtta for Redlo Eaglaccrc. (l) ft c$oaeoualJ'' ltrt.s tbtt grounit rtt.tilr.tlon Bal, ba !.gl,cctcil for dictraccc lcsc lbra 10 ravclongtb8r but tbr rD,rrela coaa out tbout tha EaDa.

(c) E = '7?lb. __4._

E - Fl.lal !tr.!gtb 1lr 811!!rol,ts p.r actcl I = Cu8laat rt b!!c o! antenar ta eupcrct b. - Eff.ct1r. brLght of tb. r!t.B!r A = Wavclcagth, ra!. rrll'ts r! b. d r Dlgtrlca 1a tdlouctcre lateaat Celcuhtlgaa Thr fo1lorlng brlcf ltudy of tbr chelrctolL6t1c! of !bo!t tF l.Bt.!'!ra 1! rer? anrJghta'{pg, aad rlll lot auch t.: tha atudG[t! abJ.Ilty. Also acr a! htcrarttng dlacuae-.oa by Ert ph111lpr. (4)

A!,tra!r Syst.a Reslatraca ABtcEaa ayataa recirtaaccr bclud1ug th. Lordlng co11, ney b. aeuuleal ec to].lors.

e. Iltb l1ght loadlag to agsurc constaDt tranldlttcr outlut

(conetaDt voltagc lourcc), a.aaulc ant.mr curreat (I).

b. f!a.8t r k!or! !.slatracc, (Rr) r.tute !o8 nad.uua entaaar cnalelt 1l atcoecrry! rad a€aaulc aBt.trla currcat (Ir)

(d) or'#--R .g -r r1

= fascrtcd t..istaaco t La ohaa I s faltlel t!t6!"ar cu*ant r1 a AatcBar sarlalt rltb Rr t!!.rteil R t Altellrt ryltGtr !€a16ta!ca I 1!r oh8a

35 rl11 bo I f.; obE! for largc couercJ'al Altallr !y6t.u f.rirtracc (tcr LF rtttllarr. 20 to 40 obE! for LF alrcrrft b..co@ aatrnaa: io ohE! fo! ,0-60 toot rertlcal rad 25O loot flat top) ead 50 rOO tyllca1 rcf,tER ratcas8.. (i! ltcr Eaglead) l! utcllrrr b'coa' aanl,1ar, tb"t b.cola 8or. r.arl'tttc to SrouEal eail fo)'iagc losaaa tlur to bigbor E-f1.lat g?ad1.!tr. t{t rat.lan hrc 2l ground radlele' ruil Ra vellor troa lOO ohac b aid-rlnter to 24O ohaa 1n ntd-'utce!'

Por.! L! tha Altcattr Porqr Ls lha rtrtanu 1l aor:

(r) Pest . !2 R. Prot = Porc! ls tbc ratanaar ratt! t = latalDa curtaDtt tnPcaea Ra = l!'taattl rJrltelr rzri'atlncr' obt!

Rrill'atloa Rcsl.ateacl Raillatlos t..irte!c. la e naaful qetb.E.31c81 flctioa. It 1! th' !rri!t.!cE thtt toql.l dlacipetc tbe s.6. .ae!8y !r 1! actuallt t:rill'at.d lroE thG a!t.E!a. At EF rltt lrt:gr entanaalr rldlatlo!

reriltanc. 1s hlghr aad antrua obolc locc lc ucually Ec81i8'j'b1!' thus, rtal1et5'o! tasistatc. lsd !!talrl! lapcdeacr ar. ott'E uo'd irr.rchelgtblyr tnd ratcBae rftlcleuc;r 1s hlgh. lt l,Frritb verJ gtu.. abolt lltrnllrc. tbe latarla 1a Radletloa lrlktaace 1a vcr' 1or, rlaoct ncgligibk colpereil to ohElc !.rl!trlce. Thurr r!t!e!!e cIllclcnct 1e Ycry 1or. For aagc of calculatlonr qy fav'orltc lonoula for radiat'lon rcaistancc ta ltou laalt. (5) - /b\2 (t) Rrea'160rr'(7|) ohne

Rrtd r RedJ.etloa rcslctelcr h ob!! b. r Elfcctlrr h.18bt of th. elrt.ala grYcloagtht A r !!Ea u!1t! r! h.

@g Por.r trd1lted 1! Frollortj'oaal to tbc trdhtloa lcrirtttrc!. ) (s) Pred r r- Rt.6

Prtd r Porl! raallat.d, rrtts

I r lgtraae oultaltr r!Pr"?! RreA g Radl'etl,on tralatancc, ohca

36 F1.lil Stt.lFth Cal,culatioDr It 1r cl.!r thtg tlcld 3t!.Bgtb 1a illrectly proportloual to rltcnna curr.at 8nd .ffectlv. helght lroa aquation (b), aad rBtc!!. cullcut (r). Lc lavaracly rclatGd to lat.a[t rystea leafutancr lroo cquetlon Fo! 1l1ustlatloar I brte ttbuLlted flcld at{agtb Ycrsu! antaaB. culrant aad varloqt tal.uas of aBtelaa syEtaE r.alstaacc lor 0.65 rrtt 1a tb. a!te!3a. I a€suoa a lldl'etloB rcalgtaaca o! O.OJ obn |!d eflcctiye bel8bt ot 8 qcters as tytr)lcal. 'flatt! R. Ohh. frat A!p6 Prad Flclil Sts.agtb rr/a 3OOltrtare 1 M11.

(r 2' .t51 .ooo?7? a?, r 5o .114 .0oor90 622 rr4 100 .oEl .oo0195 441 82 120 .s74 .ooo147 t82 ?L 200 .or7 .oooo974 ,Lr ,8 ,oo .046 .0000615 25L 4?

Xlcld Strcuqtb ltlceauraacate Plcld atrcagtb a.alutenclts oa 160 Ifiz tlth 0.55 tltt 1a the euteaar rcrr aade rt ,OO E€tara ead 1 411e. Rr tas rbout 120 ohua.

Dlgtelce lr{cecured, rr/a Ce].culated. rvln

9OO Mrtera' ,OO ,81 1 !'dlc ,6 7L lleecured ffuId ctrcugtb '/as ?816 of tho calculetcil vrluc at JOO actrrc, elit 50d rt oa,c ollr. Thle doca aot fo11or tb. lat.rr. dl'cteacc rclatj.oaablp becruae thE 5OO E.ta? dlstalrca lc la thc acer fleld rb.re .1ap1. lorauha ilo aot epp1y. (Rulc of thuab: lf.!r t1.ld 1! ta! ttae! ertaale helgbt. ot oac ravclengthr rhlch.tcr la grcltcr.) thcgr asagurra.ltr brvllg b..! uilc la lfcr hglaad rltb 1ta thln rocky eoLl ratl 1or coaductl'vlty' 1t la laeroD.ble to !r8uEe thet hrtrllrtioDr rkrrhcrr rlll herr norc fevorlb]'a coldltlollr raal !1eld atreagtbs rl1.! falJ' rlthln thes. l':bJ.tl.

Oth.t Fl!1d Str.lEth Moaaurooonta A !r..p reg sadc of thc apcctrua frou 120 kEz to 1E nEz to I'og cooe fl.ld BtrrBgtb E.rrut.E.ats lor coaparlaoa. Slacc the lleld etrrugth G€ter is oult .clsltlYc (aad calibraterl) dora lo 2Q pa/at only rclatlvcly atrong algrrals could bc heald. No cerrlcr-currcat slgnale

la thr 15o to 190 kEz bald rerc audlble, so cle.rIy they are all

belor 2O \t/d hetc. l f.r n.ar-by ailclaft bcacoae tare Loggedr tb. lrjolity beiag berrly tud1bl.r lf at all. ltot rurlrislagr broadc..tlag !tr!lo!E arc all qlrl,t. 6t!oag. IE th. EI reg"j.o! 1! thc deytlEc oEly

JI tlth rapiil fadlaS lhlcb otr. 3tat1o8 rag bcard rbov€ 20 \t/a, a!;d tbat and !til' f1eld ctrcagth l,! chatact.rJ.stld of 3ky rr"t prope6atloa, at nlght shored I,F acrsuleoolrt ptobleaetlcel. l rre'p Ead' ht' ln tbe raug' ltrtions al:' lll.ghtly ltloDgsrr rad a8!y Ef ctrtlont 2OO to 50O lrlo.

trr.au.lcy kg! _I!_ F1.].al st?cnstb ^r/E CoE6atttrtly L2t ctrE 1ro Rf,t't Ltt cIE 170 Rgrt 194 fltr 18oo lhatuck t Ja. 28 c. El1eg 201 rra 76 Frl1 Rlrer, 2? Eiler 2n trt{ Eo truatoa, 16 '{rt:qoutb, 2t6 llziw ,, S. 15 l. 251 sKR 40 Erarcoa Fld. 28 811.r 2r? P!l'l ,8 PlyEouth r 27 ullEc El'lc! ,82 LQ 29' Lta!, 29 ,n or ,4,' Stoqgbto!' 5 oJ'lec RI tro IIGIIG t?oo Prrtuckott Ito [sDE 5400 ll..dhlEi Ul t46o wBEl 485o Brocktoa, }{l 1600 WUIIR 480 Brookllar. Hl ,.44 ES! CElt 280 dgbt L?,' &, ,ooo drt

@ lrae rcetrlctlvo thea Chlrly tb. !ot.! ead astonae rltatlrtlv' ia by 20 tl'!'r' aad tb' fellot thc tlcld !t!.!gth lllltrtl.oBr typ1cal1y rlthe]'or!.!l'rt8!c.rltalalr'!t.!rldroEetoPlo.dlngctlrErk. ra .dd!.t!'oarl alr.Ertlc 1aprot.6€at.

In$iFER Fro6 tlalal !ttc!6tb 6.asotaEcat!' aad !to8 c:perJ'encr, Ei1'r at Lo algnelr 8t. ".ry rce! lndrcdi )6 1s/a rt 1 3'6 */a allalr ulaal0.)6 n/a et lOO al1ca. I tttLslt' crrli'r-cul!'at 6 !!d lOt'trER clg8elc la tho 150 to 19O kEz rcgioa 8t ) to vt/a', rcrkct' eJ,gaelo floa aay dfutrace ovcr 10 n1lcc are lovarlably REF'RENCES 1. FCC Rr1ec lDd Re8llrtl'ona Part l'5' SubPert D' by Oallcraacil operatlou Ls Pcrlltt.d floq 1O to 49O k8z llEltcil Estcr' flcld atrragth !t tOO EGtc8. of 249o/t,dlz Elcro"oltr P'r ald I! tb! 160 to 190 k8z r.81oa tb. rlteraltl"c of 1 tltt lDPut e 15 actrr alteaal plua fcad]'lal lcagtb ia pcrnlttcd' 26? 2. pltctlcrl Radio goEEudc8tios, N1leoa eail Eoraung, I)JJ, Irl6t Eatltlo!' 1968. pr8' 25-5 ,. Rcf.rcrc. Drtr for Radio Eaglaco!'ri nlftb F6IZJ 4. "Coupliag tb. vI.F ABtca!! to tb. TfrnsEittcr,n Ed Pblll1pc' Tb. IPtdoEr f-uerrct 1980 Jaclts' 1961, pegc 19-5 ,. Alt.asr EaSlncerlag Eanitbook, Bcary

3B 39 LF Skywaves and 1750 Meter Skywave Antennss by Mhhael Mkleke conscquence.Since the angle of reflection more or lessequals the angleofincidence in the fuzzymedium Reprinted with permission, from ll/estern tlpdate of the ionosphere,D layer penetrationwill be easiest both coming and going for signalsarriving at a high In an earfier arricle (Lowfer DX 1985-86:A angle. "skip" ll/estern Reponl there was some discussion of LF On the other hand. distanc€sand E reflec- propagationfrom the standpointo[ 1750 Meter tion may both be diminished for high angle signalq rec€ption over paths on the order of 500 to 1,200 making low angle radiation look more appealingfor miles. lt was assumedthat the mechanismfor such distantwork. However,our allowableERP and the propagationis essentiallya single hop or reflection radiation angles achievablewith our anlennasvery "short from lhe ioncpheric E hyer at rltitrdc of 60 to 80 much favor the acuteangle skip" mode.This miles. While the precir circumstanccs for optimum hasbeen demonstrated to be a viable option in that it occurrancesof such propagationof weak LF signals allows reception well beyond groundwave range. are somewhat unclearas yet, therecan be no doubt While it is naturalto rhink of skip propagationin that this type of propagationis anything but a normal termsof its potcntial lo extendour radio horizon, we and relativelypredictable manifestation of solar/geo- cannot ignore rhe fact thar ionosphericlyretleoed physical interactions. signalsalso retum to Earth everywherewithin the This article will review someof the mnsiderations groundwave 'skip" zone. Such lcral skywave relurns are basic to LF or skywave propagation and r":dily observedas nighrtimefading on signalswhich tentatively explore a few of rhe ways in which normally manifeststable daytime levels.This type of Lowfers and LF DXers may attempt ro take fading resuls from the differentlengths ofground- advantageof is peculiarities. wave and skywavepaths between transmil and Normal LF propagation is largely tied to the receiveantennas causing signal components to arrive behaviorofthe two lowestlayers ofthe ionosphere- out of phase to prcxluc€varying degreesof signal the D layer at 4G50 miles and the E layer ar 60-80 cancellationand distortion. These milcs. designationsare somewhatarbitrary, lt It is interesringto notethat, insofar as it exislsonly is important to rememberthat the layersare not hard- in thereceiving antenna. such fading is more apparent phenomena; edge,fixed rather, they are amorphous than real. Thc fields travellingin spaceare quite zones having particular types of predominant independentof one anotherand it is only the accident qualities. Their densities,depths. alritudes,and of their arrival times that gives us problemr With angles,with respectto the surfaceof the Earth,are all multiple antennas and a switch or, better yel a in a stale of constant flux. Solar, geomagnetic,and goniometeror other phasingunit, most ofits eltecrs atmosphericeffecls all modify the characreristicsof can be cancelledby an agile listener. thesc ionosphericlayers. Short rangeLF skywaveis at besta mixed blessing, The D layeris rellectivear VLF (3 to 30 kHz) and making copy of local signalsmore difficult while at abnorptiveon LF and MF. Sirice the D layer is the.same providing"holes" "charged" time in localinterference by sunlight,absorptive effecs are grettesl that permit reception of weaker distant signals,tn during the day, decreasingrapidly around sunset.By addition, it presentsus with a convenient iool for lhe same token, D abrsorptionis greaterin summer investigatingskywave propagation in general. than win!er. Since reflectedsignals must traversethe Dependingupon one'sobjectives, nighttime fading D layer twice. it is clear that best resuls will be problems of rhis rype can be minimized by an obtained when absorptionis lowest. appropriatechoicc of rcccivingantcnnas. I recently The E layer is reflecriveat LFand MF, providing conducteda seriesof testsin which thecarrier level of us with the medium for most ofour distantreceplion the NDB 5-322, Poinr Sur. Califomia. 49 miles of LF signals. At low and medium frequencies, distani. was monitored on a continuous chart daytime skywave propagarion is limired by D recording. During numerous trials with several absorption, ordinarily (but not always) restricting antennas.I found that horizontal wire antennas signalsto the groundwave perimeter. alwaysexhibited nighrtime fading to levelsbelow the At night, the D atnorption drops sulficiently to daytime average.Vertical antennasshowed frequent allow single and multi-hop skywave propagation. fadesto levelsabove the daytimeaverage. This would When D aborption is low enoughand E rellectiviry, sem to indicatethat a horizontalantenna is desirable highenough, evenour tinyLowfer signalscan survive when listening for weak signals through local that single ionospheric hop wirh sufficienr field interference.while a vertical is better for nighttime strength to be copied and QSOed at disanc€s of copy of groundwave Lowfen. severalhundred miles. Not all fading is a producr ofskywave/ground- The most effectivepenetration of the D layer wilt wtve interference.fu the characteristicsof thc iono occur at relatively high anglesof radiarion lrom rhe spheric layers change in responseto the many traosmitlingantenna. This is becausethe signalpath varibles which dctcrmine their moment-tG.moment will be shorterin the ahorptive regionwhen ir hasan mndition; layer heighr,deprh, densiryrnd angleall acute angle of atfack, whereas oblique angles of shift. This shifting is reflecred in a conririuous attack will resultin longerpaths within the D region, ompler movementof optimum pathsand null-Juths with greater absorptive attenuation as a direct acrosslhe Earth'ssurface and wc experiencefading. 40

(thanks its absence of groundwave radiationl ln addition.multlplc rellcctlvepaths can create to dorvnusable nighttime signals at 300 tt fading similar to lhat encounteredin the case of while laying perhapseven further. Also appealingis mixed groundwaveand skywave.No matter how we 1,200milesir iimple backyardantenna that woukt look at it, fading is the inevitable signatureof the idea of a for all the would-be Lowfers who arc skywave propaSation. produceresulb vertical. fu if this were not enoughto keep us happy, there unableto put up a we are pretty well stuck appear to be a good number of exceptionsand Personaily,I am afraid However' I would love ttr anomaliesthat creepinto our receiversto confusethe with what we alreadyhave. seemsa fairly easl issue.On a few occasionsduring the winter of 1985- be wrong about this! Since it as well look into thc 86, strong nighttime enhancementofseveral Lowfer matter to test. we might signalswas noted st t00 to 200-plus miles. These possibilities. hasit that verticalanrcnnas eients tended to produce signals considerably Conventionalwisdom NDBs arc strongerthan daytimelevels and more stablethan the such as those used by Lowfers and most radialorslike AM broad' usual nighttime signal. Vigorous, fast-moving predominantlylow-angle However. wealher fronls in the signal paths appeared to be caststations and lhe verticalsof HF DXers. terms of thcil closedlyassociated with the phenomenon.Enhanced these latter antennas are large in ground planesarc prop&gationwas clearly not reciprocalin all instances_ operatingwavelengih and their -but-it verticaland may have been in some.More observationsof comparaqlyscaled. The Low[er's Sround to the workinS thesetransient evenls are required plane are both miniscule in relation small systemstend to Similar enhancementover paths of several wavelcngth.Such electrically radiation than is really hundred miles have been observed both day and generatemore high-angle groundwaveoperation. While thereis r night, in apparentconjunction with cold fronts and desirablefor "cone directly over the vertical, the striftsin the jet stream. of silence" anienna still functions very much as a high-angle The mechanismbehind suchptopagation is as yet 'NDGS borh Lowfers and do somewhat unclear. lt seemspossible that physical radiator. Inarguably skywave signals'so the questionhas disruption of the D Layer takes place. reducing its generateusable some other iype of antennawill do as absorptive qualities either over the whole path or io be whether skywavegeneration. over one or both endsof the path. lfsuch disruption well or betterfor antennasoperating less than r does occur, evidence may be found by observing Horizontal ground are known to generatc VLF signals propagatedvia Earth-D Layer wave- wavelengthabove the radiation. Such mode. On the other hand, perhap the LF a healthy amount of high-angle Suide proven quite effectivefor enhancementsare evidenceof ducting betwcen anlennashave always bands.ln parallelthermal boundariesor betweenthermal and single-hopcommunications in the amateur Meterswe ionospheric layer boundaries.There can be litlle attemptingto extend the conceptto | 750 question but that weather has at times a major immediately run afoul of a couple of serious influence on LF propagationand it must be taken difliculties. into considerationwhen we becomeinvolved in any Our horizontal antcnnawill have to be leryckrsc -mile kind of weak signal work. to ground in termsof the I wavelengthswe use. ln any case,it is clear that theseoccasional events Thanksto therestrictions of PartI 5 of ihe FCC rulcs' olTerboth Lowfer and LF DXer uniqueopporlunities our low antennawill alsotre very shon in termsofits to accomplishthings which would be more difficult operatingwavelength. So we find ourselvesin the work or evenimpossible under normal conditions.The ex- position of a 160 Meter op€rator who has to perimentally-inclinedcan deviseany number of bX t"ith a five footantenna he can only gettwo fect run studiesand proceduresto develop a b€tter under- off the ground! ( [:t us not forgetihat he canonly standingof theseevenls now clasilied as exceptions I watt is well.)To put thisdismal prospecl in othcr antl and anomalies. tetms. our radialion etTiciencywill be very low While such unusual events may be dilficult to what little radiation we do produce will be almost unde-rthe anticipate, the vast majority of propagation is entirely spent warming the Sround srseof whal cyclical. There are Earth-basedcycles. which are antenn;. Still, this isonly a slightlyworse verticals.A litile diurnal. seasonal,and annual. Obvious solar cycles we facequite successfullywith our plac€ work wonders on relate to the solar rolation period of approximately radiation in the right can 28 days and the I l -year sunspotcycle. On a micro- lonqwave. quite easily' If a horizonul @smicscale, fading shows distinct minute-tominute iesuls can be tested at night than by day at patternswhich can provide valuable clues to antennais heard much better of 20 to 50 miles and il prevailingconditions while giving the patientlistener rhe relatively close ditance 50 to 150 mileswith the numerousopportunities to {ish out the weak signals. nighttimesignals are heard at daytime signal very weak or non{xistant, we can mode is op€rating' Slyweve Antcnnrs orettv well assumea skywave 'l'he questionperennially arise{ in l,owfer circlesas Supposingthe experimenthas been successful to this qualityof the to whcther there is a praclical skywave antenna ooint it witl be usetulto determinethe which would be more effectivethan our typical toP iignal relativeto that from a conventionaltoPhatted be hatted verticals for launching high-angleradiation. virtical. ldeally, a comparison vertical should The conceptis very appealing.What fun to havean located at the horizontal ttansmitting site, with due antenna that produced little or no local impact care being exercisedto avoid mutual coupling 41

between the twp antennas.Observations may be Meters long with loadrngcoils at the midpoint. This simplifiedby wing a phasingunit to null thedryrime sntennr should b€ somewhal independentofground groundwaves then watching strength and fade and the problem of unwanted verticd polarizarion patternsof nighttine signalsas the slywave comes should be reduced. Unfortunately, we are now into play. bringing our 15 Meter antenna lo one-half wave The ultimate testof any l,owfer skywsveantenna r60nance so the combined oenter inductanceand must be its perlormanceat severalhundred miles. associatedlosses become very large indeed. Short of However,it seemsunlikely thai any antennawhich going to sugrrconductingmils, about all we cando is fails to exhibit easily detectedskywave properties make the radiatingelements as massive as poesible. In within 100 miles will perform any better at greater order to keepthe slstem within the letter of the rules, digances the transmitter (or st least the final amplifier) will haveto be mountedin thecenter of the dipole.Unlcs lmplementrlirn this central feedpoint is acccsible to the operator, The simplestantenna will be a horizonralend-fed tune-up is going o be a real problem. Adjustmentof wire, 15 Meters long and as high as possible, the coils will be critical and it will vary with small inductively loaded rt one end and insuhted at the changc in antennaheight. A cut-and-tiyprocedure other. Lmding losseswill be high, anlenna cunent might be practical, wirh linal fine-tuning done by will be low, and therewill probablybe more elleclive adjusting the heighr of rhe anrennawhile watching radiationfrom the downleadtoground thanfrom the field strengrhand supply current to the finat antenna proper. This will be vertically polarized amplifier. radiation, tending to obscure the experimental Various loop configurationsmight also be objedive. Efliciency of this versioncan be improved considersl though, once again, allowable antenna somewhai by replacjngthe single wire with a wire dimensionsmake prospccs for sucoessrather dim. In parallel"flattop" cageor type wires,or a narrow fan working with loops, locsesshould be minimized bv or someihingreally masive like | 6inch culvert pipe, using the largcstporsible diamercr material. but all the basic problems will remain.Still, it is an Alternatively, experinrn6 along thcsc lines migftt easy antenna to build and something might be be purued un&r FCC Parr 5 cxpcrimcotrl limc to playing learnedfrom with it. eliminatethe artificial constraintson antennadimen- Some of the problemsof the simplestantenna can sions.Given a horizontalantenna producingground- be overcomeby going to a loadeddipole conligura- wave levels comparable to a 1750 Meter vertical. tion. This will consistof two horizontalelements 7.5 what will the skywavecomparison be at | .000 milts?

SKY SXPERIMENTS by l"{r ch.a t H i daka

Aft.. codpl.ting th. .bow. a.!iclc I c6tsbliEh6d a nct trcaa6i!!.r sr!c (d.sitn.t.d SKY) rnd iEpl.o.n!ad E.v.rs! prciu!.!iona of thc ho.rzon!Al t.snssitrinS .nt6nn.. Tho .xpcria.dts idclud.d c.ntar-fcd dipol.. .nd-fcd ra.. .garnc! Sround rnd aad fcd riFc aBarnlt vrFioua counloapor!c conf lluFst ion!. A! ocrl iqr tagtg rith vc.y thort v.Ftlcals hava deronat.st.d, .vcn . fcr f..t of va.!ic.l RF cur.cn! flor rill t.n6.a!. quila r Eroundrsv.. Onc of thc E.jo. ch.ll.nEcg rt SKY raa th. cxeluaion of v.rticsl RF conductorg. I'a not sura th.t iy affo.!! r... .v.. coopl.t.ly aucc6llfql in thrE ..gr.d. Porcr rag sdjua!.d to p.oducc ent.nna cs.r.nt cqusl to th.t in tho v..ticrl rnt.nn. a! th. 22 ait., roao 700'.bovc SKY !^a L,/4 ail. to th. Nf. ln .lI inalrnc.a. SKY p.oduccd r.rk tfoundrsv. ait^.ia th.! r.rc rudtbl. to sbout 40 Eilaa cnd uaaful to pcrh.pa 20 Dil.a. (22 -3OO Sroundrrvc 6ilca.) In no In.lsncc ras dAy!iaa copy of SKY.chi.v.d rt Loo allrr, bu! possibl. t.!c.a of !h. €i3d.l rc.c hcrad on s fcr occacion!. No lraca of th6 signal raE avoa hacad rt nr8ht ri l0O Dtl.E. L.t.r, thc ho.izontsl cyFtaa ras rcplaccd rr!h . susp.nd.d !ophrt v.Fticrl ovcF . chickcnri.. and rsdirl Sroundpian.. Hi8h.r .nt.nnr .ffici.ncica th.n 22 rcrc schi.v.d but !.oundr.ec fror thtS adtcnnr r.r.in.d I to I dB bclor Z2 (id.ntical cu..cni in v..!icrl .I.ncnta of thc 3ar. h.atht). This diff...nti.l appaa.t to bc r contoquanca of tcararn snd vagatation abloaption. It r.i.int !o b. g.cn rh.th.. thc gkyr.v. pot.nti.l of tha tit. l! [iaa!.d ln s !ltil.. f.6hion. Aa faa ea th. hori2ontal lntcona! at SKY rac concarnad, t! .ppc.rc th3t th. r.di.t.d ailnal r.r o.d.ra of r.tnitudc too aE.lI fo. !h. pFodqction of r d.roctlblc !kyr.v.. Horcwor, !h. ho.izontrl .ffoF! r.! hupcrcd by l.ck of h.ighti th. b.at th.t could br achi.vad ra! .round 25 fc.t. Hld it bc.d goaribl. to auagand antadar and tranaaittar tt 50 oa l0O faa! a.aulta rould !u..ly h.v. b.cn . blt ba!!... Bu! cuch idatell.tiona g.! ua 'backy..d' r.th.. quickty out of th. rF.. oa f..aib[. idrtell.tiona, .rp.ct.l ly if tncidanlaI e..tical .Adl.!ion ia !o b. .rcludcd. Ovcrsll, r.tultt a.. incodcluaivc bu! ault.a!ivc th.t utaful horizontrlly pol.rizcd LF t.rnlDitttnl antcnnra r.c not .rtily produccd rrthin !h. conltrrinlE of Ptrt 15. |,')

Effecte of llolsture on Insulated and Non-lnsulated ground radlals By Les Rayburn, XMGR

For several years mny Losfers have notlced that the ERP and antenna current fron thelr transnltters drops durlng perlods of raLn, snovfall or other molsture. It was declded late ln the 1985-86 season that the MCR site should be used to lnvestLgate thls occurence and to document the extent of the losses caused by ground molsture on varlous types of ground systems.

The I.D. cycle for the UGR beacon was nodlfled to include periods of long key-dom (20 seconds 1n length) durlng which tlmes oeasurenents were taken frou a antenna current neter at the slte, a 1ocal F/S meter at the slte, and a callbrated F/S meter Located onboard the USS Ulysses S. Grant SSBN 631 which was undergolng overhaul at a dlstance of 1.3 nlles.

Three types of ground systems were evaluated; a system of burled bare wlre ground radlalsr Lnsulated wlre radials 1ay1ng on the ground, and a snal1 elevated counter- polse ground systen. The testlng perlod last.ed for two (2) months and over 400 readlngs sere taken at various, randon tlmes. The weather durlng the tests ranged from a long, dry perLod of about two ueeks to heavy rainfall, and a ltght snowfall.

The ground systens perfornance dlffered radlcally as follows:

Burled l,llre Radials: Losses as great as 4 db uere notlced ehen uslng thls type of ground system durlng perlods of hlgh moisture. Horning der could cause losses as Breat as .5 db!

Insulsted lJire Radlals: This system was a better performer, wlth losses of only about 2.2 db under L'orst case exanples, MornLng dew had lltt1e effect on the output and "recover" thetsysten seened to nore qulckly than the buried wire radlals from molsture.

Elevated counterpoise: Thls systen was unaffected by moisture and also resulted Ln the,highest antenna current desplte belng che second smallest system erected.

**rn falrness to other lowfer lnstallatlons, all of the above ground systems were qulte snall and enJ-arglng all of the systems resulted ln less loss fron nolsture. Thooe wlth large ground systems my not notlce losses that are thls great.

From thls study' lt seems loglcal to assume that the elevated counterpoLse ground systen wlll result ln a greater ERP for a glven lnstallatlon, year round. Those losfers in the Nev England area wlll benlflt greatly fron this type of system due to the reather condltlons that exslst throughout nost of the year. (snowfall on a tso day perlod iesulted ln losses as great as 4 days of ralnl)

The reasons for these losses 1s not entlrdly understood but an effect of antenna de-tunlng was noted at the llcR slte durLng the tests. Re-tuning the antenna aluays resulted in a.2 to.8 db lnprovenent ln the output durlng perlods of nolsture loss. rt ls assuned that the loss ls caused by the return or lnage current fron a vertlcal antenna having to pass through a greater reslstance ln order to conplete lts f1ow.

Mlke Mldeke' 22 has also studled these effects and has notlced that lmDrovenenrs to hls ground systens (length) have not reduced hls losses. while others have reported that l-osses can be reduced to alnost nothlng by i.mprovements.,.this nay depend on the sol1 under a glven lowfer lnstallatlon, 43 I

Mlke Mldeke has also lndlcated that hl8 losses are not relaled to de-tunlng of the antenna through thls uas clearly noted at tlGR. Though thls effect dld not cauae the major losa, lt eas a factor ln the overall lossea caused by noisture.

So11 analysls ls avallable from nost state unlversltys and thls ay prove to be a worthuhlle project for losfers and result ln further lnvestlgatlon of thls occurence. For those oalnly lnterested ln lnrpovlng thelr ERp, thls adds to the evldence that the elevated counterpolse ground systen ls the best ground systens for those losfers sho can erect one, wirh the insulated nlre radlals laylng on top of th€ ground belng, the next best cholce.

REFERENCES:

1750 Meters l|esrern Update #21, Mlke ltldeke, December 1985.

Effects of !!oisture on Insulated/Non-lnsulated/Elevated Counterpol.se Ground Systens, Low Frequency Experlnent //003, Les Rayburn, ltarch 19g6.

Nt&kemte,De. 1987 oraundr€slstdf,e st Z2w6 redrcedto rolrd l0 0hmsthrou$ o combinstimof rodislsard tr6t€d foin6 (seeP. 47), De-tunlngcousd ry dtoruhg soll moistursG In fat @!r ot 22. Thlsprablemw6onlysll$tvslle/istedbygmur|dsystemimprwpm€nts.fby'€v€l^,&-tuningiso trrrt$lo c$dltl$ whilemoisture roloted variatlons in garndrtsistarca sre c0rbi&r6bly more lntrct$le. ln myexg€rl€tf,s st 22, yst€tn efflci€ttcyls hlgh€stwhen the furtd ls very dry t0 a &pth 0f 4 festr mrl. Ewnwith croful re-mstdllm,ilt€nnE qrrrent ffilctlons of 50t to 408 are 006ervctwir€n the uoDer few f6t of soil bomes soturotd. Dtato tlp dlfflorltyof m0kingprsisist m€Gurementsf,d theuncertainty c t0 holvvrlfl$ rolot€d16 fehrs cdr be isol6td, lt ls hrd to sa'/ tbw imprtd|t srdl saerni$lylarF ground vrlotlms reollyrs. Ct|moto,the nsture of tlp soil6rd the ilt€tlno slts ltseU will all plsr/6 mle In et€rmintngvrhether this is dr lmprtfit ptEurdm....r vthetEr it dl beobs€rvd st 411.....

FERRITEtO\DI}IG F6fflt6 ss lodttB collsIYILL wrk. There6rs 0 fef, thln$ th61se lmportd|t.t0 r€memb 6[orittlslngfe6lis. F€i"rltetffi lmrm et(ponentislly6 po'wf is iogre6€d,$ whot mr/ soano(collmt frun o rolviry storsoint mry bewrso thil ussl€sswtEn calld updl t0 h8qls evma llttte porer. All ferrlt€sf! mt ttE sdne. TIBwroru m0t€rl0l ca m*e 0 bd sitmtlm rrse- tFelit$ permdlllty, LFmatetrlols drl 6/oldthlns lik8solv# BC6l$tlcks. Sclv$ matrlcl frm TVhl$t,/oltry*pplles l,lstd A fefflte loitd oll thothG 0 sluoth0t ls elt Er ctllbrot€dr l@kSlels v€t'ylrsEful wlpn lt cmr€stlme to cmstrl8t! lr$ atr-cre coll fr o o

Ovcr thc years I'vc attcmpLcd to radiate LF signals froo a number of girc€. Tho nogt idportant lagson learned froa a numben of fai.ly sorious instal latians has been tho virtuo of putting th€ entenna ln the clcar.

The accohpanying drawing i I lustratos 3 rcal inatal latiens, cach conai€ting of a 32 to 36 foot v6rtical f,ith eubstantial cap4ciLy tophat and idonLical currant in tha antonna baee. Thc rslativs signal lcvele arc for groundwave at digtanceg froo 25 to 22O nilcs. Site I ha€ navcr bccn haard beyond about 50 trilcs. Only SitE 3 has El€nerat€d r vcrifiable ekywava signal, though it Ec6Dg Iikcly that Sita 2 hae skywave potcntiel. Sitc I iE rooded, Sitc 2 nostly brushy {ith scattered oak and pinc trecs. Sitc 3 is su.raundcd by brush renging in hcight froo 2 to I fact. Howcvcr, €xcept for a narror ridE,6 rising to thc flcst, thc ground drops aray vcry stcoply fnoo Si!e 3, lcavi.nB thg antcnna cascntially tn the clgar.

ThiE EugE,csts two bain points: 1 - Givan I ratt lnput cfficicntly utilizcd, th6 EFFECTMNESS of thaL povcr can vary by"" a *' - i : :i ;""; : "" : nI:'"" i n lo 3 ;.3 :o":" I :" :, i i:: : . - " :::::?::,':"::'":l:::":':;"i".::T:::::l:".

Not Euch sc6ds to havc bccn donc rith high levcl LF transaittinE, aitrs. In vier qf thc potcntial porforElnco, guch gitaE Ec€E rcll rorth considorln8. Thcrg arc drarbackg algo rorth considarlng: cffcctivc 6nound €yBt€a€ don't conc aasily on rocky pcaks, rcootc control bccoocg aloogt €gacntial and liEhtning hazardg arc incncascd in hi8h, cxpoecd placce.

9tTf 3 +t70c FT *4 lg

StTEr. +,66 FT + t7d8 BT'TDX I - 5O aracr Q'llO-rrer - J 2,ooo+^,t,t

5rrr1 / O dB Laa/s6o crort / r, tcctton,Looktn,! v.

44 . TRANS},.IITTINC CROUNDS FOR 1?5O I-IETERS by Michrel Midekc

folloring __-_ th" Datarial ig drarn fnon aarly is€ues of ths YESTERN UPDATE and froo nuncrous unpubltehad notie.

The axplanations thst bcBln thiE scction probably lqavc uuch to bc dceircd froo sn aneinacring standpoint Lut thcy ghould at point Iarst fsirIy cloarly to thi kind of aituatians rhich Dusr ba addrcgscd by ground €ystc'g to bc uaad vith radtators that a.a alcctrlcally vcry Eho.t.

Ground ayst6Ds for clcctricglly short radiators nccd to accoapl ieh tio thinEs: thry DuEt cltabI ish r lor-rcBtstonoc canncction rith th. carth and thcy Eust scrcan thc lntcnac clactrical ficld fro' thc loesy ground gunfaca tn thc in'cdiat. ,vicinity of thc antcnna.

Short varttcalE Ara clactrtcal ly lcngthcncd by-" tnductlvc loeding to bahsvq tn Dany rasp€cte as if ihcy ,""" full L/4 rcvc long. ln cffact, thc radiatind alcDant tg ogdc to look likc g half of l/2 rav6 dipolc; thc ground ay€t.n providce thc othcr half.

ln a dtpolc, aqual currcnt flors tn ctthcr hrlf. tn thc caac of tho dipolc forucd by our short rtdiator and its lround aystcDr thc rcsiEtsnco of tha ground half ts inv6riably f,igh"" than that of rrdiattng hsIf. Thc curront thst flore tn thc entcnna t€ ltDitcd by thc highar raaiEtancc. So tha nonc tha Elround rcglatanca can bc rcduccd thc Dora naarly thc antanns aystsD rill approxiDatc r vcrtical dtpolc ..d .th. EoFc affictcntly tt rtll pcrforn ss a radiator.

A BiDpIO lround ayst6B conslst{nE of a ground nod or tro rnd pcrhape EoDc aonnaction to looal plunbing Day ba aonc or l€s6 satiafactory at hiEh fraqu.ncics but on LF it ls of dubroug veluc. Ground rc€istanca uay bc 100 ohuE or aorc, 8nd tt ts clcarly dcEir.blc to iDprovc tha sttuation. If ground rasiatancc cannot bc brought to a Ior valuc, thcrc arc rcsl ItDitE a6 to hor far it tE rorthrhilc to Eo tn rcduclng thc r.Eigtancc of ('thar p.rtE gyst.n.,...I- of thc Litz,ln€ and a gold plrtcd antcnna rtll bc a r8sto of cffort tf tha ground ts no good.

PRACTICAL GROUND SYSTE},IS - Scvcral D.aBu.cE Eay bc undcrtak€n to rcducc ground r6Eistanca. fhat rpprorch or coubtnation of approachce'Eit.r ttil bc Doat vgluablc or practic!l ri I I dcpcnd on avai lablc rasouncas and th6 anbition of rhoaver has to do thc ronk.

THE OPPORTUNISTIC APPROACH 'radial' iE to run a to cvcry llroundod for Ju€t nagalval natal obJact rithin raach -- plunbtng, fencag....buricd nctal of al I sorts. Eleh wirc should lcad to only ona carth conncctl.on and alI rirce should ba brought to a cantrel point ncan thc bagc of thc antcnnc. Assuoing anoutn Datel can bc found, thia p.occee can continua untir furthar additlons producc no ucaEurablc changc rn lnrann! ourrcnt ar tunlnS. Yhcrcvcr posEiblc' conneetiong should bc soldcrcd. Clthcrri€c, us. braes, coppcr or stainlcss atccl "fiif"-'""a conncctors. Avoid sluDinun snd iron. If you ncqd t; naka connaction (or rith a rusty rustabla) iron pipc, an oxy_acctyian. 46

re ld ine torch crn bc qged cither to bond haavy ooppan wirc dircctly or to braza on bronzs connacting hardwere.

llhcrc connectiong eugt bc Etrictly mechanical, try to Dakc th€E acacasabla for futurc clcaning and poliahine,.

Yhan adding opportunistic grounds, it is a good idca to Eonitor both trlnsDittcr pqrformanco and signa! lcvcl. (Bost tf signal is nonitoncd froa g fcr wav€lsngthE asay.) Somc grounda or coDbinationg of BroundE turn out to ba count€rproductivc; Dora is not alrays bctt6r. As grounds anc addcd, antanna curr.nt SHOULD incrcasa rhi lc loadin6 lnductancc snd/oa capacit ivc tninDing ahould dccrcaEc.

- RADTAL CROUNDS A norc foroal approach to thc Elnound systco l€ to con€truct a Dat of radial f,ircs ccntar.d undar thc vcrtical. Thcrc, aE iE thc casa rith Lorferg and Dost NDB8, tha antcnna ta vary Ehort in tarms of opcratinlr, revalangth; tt appcarE th€ra iE littl. sdvantaga ln u€ing long rsdiala { on thg ordcr of l/4 ravelcngth). This ts c6pocial ly trua if tha opcrator lE qnrillin6 to install at lcast l0O euch rsdt6ls! In practioc, radiala 20% to 50X longcr than thc vcrtical itEclf ttll rork vcry ralI. If ona has s Dila of rirs to invaEt in radial6, It rilt probably bc b€ttcr to cut tt tnto aany 35 to 70 foot .ecctionE than to uso it all for thrcc or four vcry lonB radials.

ObEtruct iona such as but Idings, tracs and proparty boundartcs can rcndcr thc rcallzatlon of a Eybn€tnical radisI Bat tDPoEEibla. In thcga altqationg anc Dugt Jugt concantratc on doinE rhat t€ practical. Mckc .adlalE long whcrc you cen and try to sprcad thaln cnd6 spart ao th8t di€tributlon ls norq on IoEE avcn rtthtn thc construints of tha locat ion.

It ts battcr to hav. radills on thc Eurface thgn burlcd snd bcttcn to havc thcm abovc thc gurfaca thrn lyfng on tha ground. If radislE rrc buried or ln eontact rith tha aurfacc, thcy Ehould bc InEul!tad; othcrrt€c contrct rith thc loesy gurfacc or iDDadiatc gub-gunfacc rt I I lcad to unn€ccttgary loggcg and .xeEicratc thc do-tuntnfg that rcEults fnoD va.yinE soll [olgtura cond i t iong.

It lE oftsn total ly tnpractical to clcvsta thc radtal syEtcD. SoDatlm.a rldialg arc burtqd JuBt to 6ct thcD out of thc 'ataplc- r8y. A practical altsrnatlvc to burial is to radlele to 'U'E thc ground. Juet uakc a bunch of of hcavy (loga to l26a) eolid rira, tn tnch. or lcsg ridc and 2 Lo 4 lnchcs long and qga thcn to ptn thc rsdlalB dotn cvcny fcr fcat. ThtE rill prrDit larn DorinE3 snd un-trtppcd foot traffic thi lc DintDtztng _- !alntainanc€,

RADIAL - IIRE SIZE If rc viar el l of thc rudralE as paral lal conductor€ cach carrytnEl r roughly cqual gharc of thc RF currantrlt rould rppcar that onca thcrc era a dozcn o. Eore rsdi!la thc r.€tattv. loaaa€ tn th6 radial sy€t€E b"coro qrit. soell. Any rirc that ts hcavy cnough to bo duiablc,1ll b. pi".ty btg cnou6h to handlc tha currant.

Horcvcr, it ron't hurt a bit ff you DO u€c Dassiv. r8dirla. Early parker in 1987, Lorfer Jcrry (ClyR) hoiatcd a Dodcstly tophattcd rirc vcrtical abovc a groundplanc that consistcd of lOg piccaa of CATV hardlinc. Thc lcngthe of hardlin6 vant.d froa 25O to 4O0 fcct ! This lnstal lation ,as an out€tending succos€. fould ragultg havc bccn ae good had thc radiale bccn Ehortcr or nadc of sooCthing Itka *22 hookup f,trc?

Thora ts na vtrtua at all tn having radiale that aFc 6ith6r not conncctcd or arc poonly conncetcd. Again, SOLDER $HEREVER POSSIBLE and taka €pactrl clrc sith purcly ,."niii".l connact iong. I

+lt-

- CHICKENYIRE 9irc ncgh rcal I ty ronke. tn e pontabl6 inetal l8tion I had a tophatt€d wirc vcrtical rhtch initial lv rag euspendcd over 12 thirty foot radials. Thera rcrc four !ho"t Erqund rodg and a couple of connaetion€ to pluobing and fancing. It I fatt tnput tha antcnna currcnt rge a digcouraging 60 Da. Then 60 eq. ft. of ocgh ras placed dircctly bencath ths entcnna and conncctcd to tha Elround systaD, antenna cu.rcnt doublcd and loading inductenca raE rcduccd to a coreepondin6 dcgrec. An additional l8O aq. ft. of 8EEortcd DcEh Ert6riaI pnoJuccd only Dinor improvemsntS.

In a aubscqucnt ln€tsllation at anothcr sit6. a norc rcfincd approach ras takan. An 8' x 20' roodcn framsrork ras con€tructcd fron planks and 2x4e. l8O eq.f!. of l- acgh w8s attachad to thc uppcr €ldc of thc francwork and floortn6 ,ae natlcd ovar thc €cracn to provido rorkepacc and a platforu for thc trsngnitt.rr battcry, ctc. Radial€ (goDc rith ground tcreinations), ,ars cxtcndcd fron thc cdgcs of tho gcrccn ractanglc, No carth conncctlon rart aadc tDDadiatcly undcn thc antcnna. Thta arranllcDant hae provcn qutto €etisfactory. In coDpaniEon to a convcntlonal radlal uat lald on thc 6unfrcc, thie eyatcn acaDg to bc -ralstivcly innunc to tuninE ehangce eauead by variationg ln 8oi I Doiaturc.

- cHICKENYIRE oN THE RooF so.ctiDcE roof nounring offcre thc bcat ray to Cct an antgnna lnto thc clcar. And sooctincs tha roof la thc only availablc.ntcnna sltc... Chtckonrir6 DaEh can ba uScd - to advant8€6 hcrc .ithor on top of tha roof, tackcd to r.ft.rs i6ecdiatcly undcrncath or siDply lgid out on th. ccilin€ Jotat€. Elcvrtcd radtala or dornlcad€ toaurfacs radial€ and groini rods can bc run fnom sldcs and corncrs of tho butldlng.

- RADIAL TERHINATIONS tt ta probcbly aorc hclpful to provid. nuDcrouE ground rod t.rDinrtions for radi.ls then to attcnpt a sarth -m8ssivc .connact.ion dircctly un!9n th. antcnna. . -4__qaqa point is thc tran€Dlttcr lnatal latlon 8t 22. Thc lnitial configuration consistad of around 120 thtrty to slxty foot radialE and a ccntral gnound con€i€tinE of oopp€r pipa pcnat.stlng about 12 fact in a trcated pit. Latcr, rnothcr 2O radi8la 4O to 7O fc6t long ycno addod. Thaac radialg rars cach tcrainatad rith s trcatcd coppcn pips ground. This ahangl. - -6urrant. r;iu:l tad ln a gub€tant {a I lncriaea in ant€nna Furthcrnorai thc ccntral ground no lonElcn drcl ncagurablc eunrcnt or uadc any othcr apparant dtffcrcnco to antcnna AyatcB pcrfornancc. I bcliavc thc td6al objcctlvc hrr. l! to Daka thc cffcctlv. diaD6tcr of thc carth connactlon.bout thc aen. ra thst of thc radlal Dat.

DIMINISHINC RETURNS - Onc of thc sad facts ebout ground lmprovcocnt i€ that thc uora you do thc lcgg raturn you Ect for cach hour of labor. Thc ftrst 3 or 4 rsdials or llround rode produec lDncdlatc and {oprcaeivc rsEulta. Thc nrxt for rtll pnoducc ncagqrablc but lcgg lDp.aEEivc rcgultg. Aftcr thrt you havc to rcally rork to a.€ that anything q! all ls bcing acconpltshcd. A rough but practical rulc of thuob for thia gont of rork €ays that, for a uEcful rceult, lt ts ncccEEary to rt lcaEt doublc thc nqubcr of 6lcD6ntE alrcady in placc. If you havc a dozcn radiale dorn, adding on6 or tf,o Eora la not likcly to ehor a ncagurablc lDprovc6cnt (if tt deas, gtop ri6ht thcrc rnd figurc out rhat raE rrong rith all th€ OTHER radtale!) but thc addition of anothcr dozcn ahould havc 6ooc po€itivc cffcct. Tha ncxt gt€p calle for a oiniuuu of 24 Dorc. Hor uuch lE cnouS,h? l1y own facltng tE that tf a pcrson Dsnagcs to put out 3O to 60 r8dials and lO to 15 ground rods, hc hge sarncd hls ra€t. Its tiBc to sit back for 8 fcr Donths, gcc hor lt ronkg rnd acrlously conaidcr juat rhat thc ncxL lcvcl of iDpnovaDcnt ta rcal ly vorth. 4B

- -coppcnclad' CROUND RODS Bcwarc of thc chcap rods tntcndcd for uae ?ith TV recciving antennas and tha likc. Not only arr thly rathc. ahart, thc thin coppcr laycr ie oonc likc paint. than platinE. What doaen't acrapa off whcn tho rod iE drivan f,ill vanish in a fcp Donths and you aill bc lcft f,ith nothing but ruaty lron In thc ground. Uec hcavy duty coppcrclad ground rods, 6 f€at lonE lf you can poesibly Elct thgn that dccp, Or usc coppcr pipa. Evcn thc thin 1,/2'Dat6rial can bc rorkcd dorn to coneidcrablc dcpthg if onc ia paticnt.

PLACING CROUND RODS - I'vc found a po€tholc diggcr to bc Dosr hclpful in placin8 ground rode. UEing tho posthol. diggcr and a taDping bar, dig out a E'to lO'diao6t6r holc as dccp ae you can convcniontly Daka it. 2 1/2 to 3 fact is usually fairly casy. Thcn placc your g.ound rod in thc contcr of thc hola and driv€ it in ss far as you can. ,fith thc right eoil and_a bit of luck yau can 8rt thr top of tho rod all thc nay ta thc bottod of thc hoic. lhilc you can still raach tha tap of thc rod, accurcly aolda.. lsn€lth of $14 or hcavicr coppcr rir. to it so that you rill havc gomathine on tha gurfacc to maka conncctions eith. Bcat to do tho €oldaring qftar thc pounding is all ovc.. Thi€ is proprnc torch rork; eolderin8 irons aon't h&ck th. job. Sandpapcr all eurfacce, t in thc rod i f you havcn't a lrcady donc aor takc Bovcral anug turna of rinc around the rod and flon eoldan ovar thc vholc thind.

- TREATED CROUNDS A furth.r bonus of thc postholc tachniquc ia that it lcrvag you all sct to aakc a trcatcd ground. Oncc thc Elround rod hag bcan drivcn as dccply into thc holc ss it ia goinE to do, thc holc can bc rcfillcd rith a eixturc of drrt and rocksalt or coppcn sulphltc. (Tha galt blocke sold fon livcgtock conguEptton arc inaxpcn€iva and can ba brokcn up to providc glos- disolv ing hunks. )

As thc cryatalg digsolvo in rain or rrrigation ratarr . conductiva aolution bcgina to eprc:d throuEh thc holc, .xtcnding both drapcr and outslrd. Thia incrcaaag tha offcctivc volunc of lha csrth conncction, raducind thc ra€istancc of that conncction. If acathctica .nd Bafcty pcnnit, don't coDplctaly fi I I in tha po€tholo€. Shallor dcprasaiona lcft in thc gurfac-c rill gathc. r!inxatcn and focue it on lhc aoil {and rod} undcnncath.

Thc tr€.t6d holc tcchniquc can bc furthar claboratcd by diggin8 a bigdcr hoi6. Xakc a pit that is lsrElc cnough to cliDb into. Takc care that you ara not digging into material that can collapec g around you, and 6o dorn or-g icct. Drivc onc or Dor. rode into tha bottoD of th€ pit. Thcn I inc t.hc pit xith chickcnwi.a to p.ovide a nicc canductive armatura to Aupport about a 2- thickncee of clay. Thc clay nork can be donc' in atagccr of r foot or so. Fi I I in cach lcval f,ith soi I snd ehcoicalg as it is lincd. Thle proccdurc js a LOT of tork but rr doce rceqlt in a larga- dianctar, dcsp treatcd ground. Thc clay lihitE di€pcrEion of thc canductivc solution. Th.Fc ia no nccd to buy cxpansivc pottcrs. clay. Find a claybank and dig out,h4t you necd. Discand largc rocke and ignors thc emall onci.

Al traated grounds I si I I tend to rmprove over t r&c, csPecially if proviaion ie oade to rencw th6ir trcatbcnt cv ary yoar or tro. 49 - HAZARDS Both coppor sulphatc (which is narketed aa root ktllcr for scptic systcDs) and rockaalt can bc d6€tructiv. to plan! lifa. l,laggivs injcctions of chamicals into the ground ehould not bc pcrforocd f,ithout duc con€idoration for potentlal daDaga to vcgctation or eroundwatcr contamination. Whi lc coppcr aulphatc ia suppoecd to be most cffectivs in incraaging conductivity, Cralt ia noarly as Eood and coneoqucnccg of contamination oay ba lcgg s€riouB. DiDinishing raturns apply in this araa se rall - thcrc ar6 rcal advantagcg to anhancinEl conduetivity imn6diatcly around yovr ground rode but gaing on ta aaturat6 tha neighborhood pon.! makc all that much diffcrancc to your Eignal.

TAXE ADVANTACE OF CIRCUHSTANCES - f,hcncvcn thorc ia constrvction or an sxclvation around thc plac6, naka gurc you havc Bon. coppcr rt thc bottoo bcforc tho holc dats fillcd in. Do good eoldcrlng and build for pcrEancnc6; you ncvrr rant to aoc th6 bottoE of that holc aElain!

POSTSCRIPTON GROJND SYSTEI1S The redr wlll notolhot lhe o(p6lths of groundsystems foJnd In thls volumo6re silnsrhatat 0G with trstmontsof thssubtect In HFild Broffit Btrtdlitoraturo. Thlsls not entirolyilo to themytt$ ot Lovfor(bm-Ttre rol golntls thato|lr Ultonn6r€ VERYstprt, E-flold q$orattng&vicss whldr aro pl4uodwith dlfftrontkln(b of lm thfi tl|60 lmurrsd by mra off entr lgnt€drdlotors.

tot PorEn ANfEIINA CURIiENT& POlrEN ilETER IhYe Johnston, 9HDQ

Thls neter 1s e relatlve lndlcatlon devlc" lon3ltlva anowh to hcalur! tJrc antenna c[rent generatcd by a CI4OSchlp. CaLllrate lt for Porer by rrslng a non-lnductlve lGd rcalrtor and lGasurln€ thc leC voltagc yr.th a recope or RF yolinetcr. P (xatta) - gz/n (onro)

S"t full-Ecale dcfl.ctlon 6ensltlvltJ rlth Dotenu.oneter R.

to ^nr.*g1l t" r"t'..-5ll

T. - TJ0-6 (substltutton 0K). Prl.- 10t #24 \ lnt/Xntr nal bc tnterchanged). Scc.- 2Ot ll24 ( nay br lncraaaed for gr"at"r tcnall,Ivlty). Ei- lrldqe rcctlflrr, use four 1}t9l4 or cqulv. n--5hohnspot.

l,! - - J0 ul full-scale neter. A l"sa Bensltiv. Det.r xlll r"qulrc nole Becondary tuns ln T. 902Jt raceptaclcg can be ueed at lnput. 50

1750! RESISTAIICI BRIDCE

by llltchcll Lcc llhca dcrigohg flltcr!, tltchlog trlnrforDcr., rEd rit.utrr3 for 17j08, lt It lolctlocr oGcclalry to t!.rurc rerlstlacc tt th€ operatlug frcqucncy. An crccllcnt lor frequcncy aolac brldge her bccn dcacrlbed by Stlrllog Olbcrg (Prgc 17, Dcccober 1984 LOUDOSN), but r fcr llopllflcltlonr cro b€ tade. Thc torold chorcl yag a T200-3, end lt rcqulred 88 trlfller turDs of rlrc. Io .ddltlo!, e verleblc 365pF capecltor rac added to Dull rny rcactlv. cotspoaent. The utttltty of thlg crpacltor .t 17500 1o gueatlonablc cooelderlng that lts rclctrucr l! roughly 100 tlo€s thc reslstlve conponeot of a typlcll 17500 tttcona ty!tc!.

Thc adJrccnt pege ehona e ahpllfled brldgc conflgurrtloo thra cla be butlt frol e rtell, lnexpcarlve PT50B-?7 torold (looke norc llke ! rlceve to e€)r rad e 250-oho carbon pot. It ls rorth apendlog noney ou e good, aolld potcotloDeter bccause the oullr arc [arror and requlre a preclsloo touch. Th€ torold lc yound rlth 10 btfllar turar of coall, lnculated hook-up ulre (26 to 30 geuge). Blftler ylrc lg nothlag Eore than r tnlsted palr. Tro 2' lengths of hook-up rlrc aad a haod drllL ulll produce profeaaloual-looklug blfltar rlrr. Tty to kcep ther€ turDs buoched up to oue glde of the torold. The larldc cdSG of eo PT50B-?7 la rough aod slll cut through enaoeled rlre so ordlaary, Jlckct€d rlre lg preferred. ghen the rlodlng {a cooplete coEDect thc tro lndlvldual rlndlogc ln aerleg to foro a center-t6pped rladlog. Add lo-tura ulodlag lo thc oppdEltc clde of the torold for the osclllator/oolse loput.

Ar far a! thG ceatcr-trppcd rlndlng: the ceotcrtap gocs to your r€celver, oDe .Bd coonect! to the unkooyn, lnd the other ead connecta to the 250-ohm carboa pot. Soldcr the torold to rultable coaBectors to oatch your recclver and grcllletor/oolcc lource. Not€ that ooe eod of thc orclllator wludlog ig "uokoro" cooaected to tround. A benlnr polt ls optloue for telolnal, although I uged e BllC. A aoall aluoluua box ulth pot attached ntll serve a6 a foundatloo for thc brldge aad coaD€ctorE.

Thc orclllatorholge Eource eln bc a clgael gencrltoE or s loud lotr€ lource. 10nV taa or nore ls recoaocaded. If the generstor ls partlcular about load tnpcdaoce, golder e 51-oho reslctor lcroaa the o8clllstor ulndlag.

Ttrc btldge aurt be csllbretcd. Tt|c earl.st rod no8t lccuElte nethod lg to collcct en a3sortneat of carboa reslstors ltr the raDge of 2.2 to 250 ohos. Co8oect a algnal source aud e rccelver and tune theo both to 175kllz. Norr rttach clch teslstor, one at ! tlo€, and adJust the 250-oho pot for a aull as obacrvcd !t the recelver. lark thc posltlon of each oull and urlte dosn the value of the re8lstor lext to thlr oark. The reslstors cas be double checked ylth !n ohDretet. If a reglator aasortoeDt la unavallable, the pot's DC rclllt6Dcc can be ocasurcd vlth !n ohutscter lt severll posltlons. l{ark thls oetlureleot !t each asEoclatcd posltloa. I have fouBd the reslstor Eethod to bc aupcrlor to the ohaoeter nethod slDcG clrcult prrrsltlca san thron off the potcotloaeter oull polnt Euch !h!t the pot rcsiatance does |rot correspond to It! DC tcslrtrace. llou tuac thc rccrlvcr aad tlgnel aourcc to your trlnseltthg frequclcy. Letrg !c!!urc thc roteuDa aad flnd out rhrt lt! rellstrncc ls. Coanect thc brldge "uok8ora" tcrolnel to the bottoE of the loedlng coll (doott forget to grouad the bt{dtcr too), aad the! tuoc the lo6dlog coll and 250-oho pot for e null ln thc recclycd tltnll. The null. rlll be qultc narton aad dcep, rnd rlgnals ou thc antcDDa often ovcrporcr the brldge algnal source. The reslstrnc€ rrtll rcprclent thc guo of the coll, loteDDa, and grouod. AD aotenDA reslste[ce ocsaur€ncat 1r Dot lEte[dcd to lubstltute for tratsDlttcr tuneup, but rather to 8,lvc a bellpark flgure for total r€slEtaace lnd ayaten efflcleucy. 5i

LOWFREOUENCY RESISTANCE BRIDGE Tune osclllatorard recelyertrc desFed ltequency. Calbrate rvth lxed carbonresistors of 2.2to 2500. AdJustcarbon potentiometer tor a null \yfrheach dilTerentresistor and recordyalue on scale. To m€asurean antenna,tune antennato resonanceand attachto bridge. Aternately adjustpotandantenna tuning for null. To checkloading coll losses, replaceantenna with dual-365pF yariable capacitorand retune to resonance.Adjustbrklge for null.

$fiErfiA(oRL6Kr{O}n{) snGLEpONTGROTJND

RECETVTN

r2so

GROTJND 52

RF Altl,lETER FOR 17500 TMNSHITTING ANTENNAS

by lllichcll Lce 172 North Trcatyfourth Strcet Sr! Jore, CA 95116

Tbc Ley ptarocter la rly 17500 bcacoB ls antema currett, yct r Dean8 of rclrurcrcBt lr ofte! very bard to flud. Typtcal 19 eoteau cur!.Ets r|rBe frou 5OnA to over 300oA, but R! r@cters la lhls currclt rlogc lrc cxtrcoely rarc. oftclr rhca oae docs flod luch ra amctar rola ruteur rrdlo opcrrtor brs bclt hl! to lt; the lrrcphc.lblc thernocouple bas long rhcc veporized bccaugc lt rrs uscd to Dcaaure thc rateDta curlcrt dellvercd by r 160l. ttF traar8ltter! A brtter ray 18 to bu1ld e riaple RF currclt probe.

Shom la Flgure 1 lg aa RF curreot probc suttrbl. for oetrutlag 50 to 500!A full rcale deflectlon (fSD). Thc cltcult coualctr of .! E-coae curreDr trusfomer, rhunt load rcalstor, dlode voltage doubler, end 1oA DC rcter. ft. curreot Y 1r raopled by the E-cor€ aasenbly. Thc prtoary le a clngle tura (prlsllg through eech E-corc vold oace), rad the secoadary ia 25 turas of 024 or rullcr legDct ylrc. Tlrc curteqt le treosfoned by thl taverae aquere of thr tuns rrtlo, so Ll25 of th. rctul BF currcat florc lu thc recondrry. lbc cuncot tteafor!.r tcflccts lcsr then rs oha hto tb€ prlury rheD .dju!t.d for 50tA RF FSD. Aaothcr my of ltrtlag th. lascltlon loss l! !!y that lcs! thao 1Ol9 1r cotrucd to opcrrte tbc rnrtcr.

A lord rcElstor (500 ohn pot) tlralEates the sccoadlry. The voltrgc dcvcloped fu rcctlfl.d aad doubled by I palr of dtodes aud crprcltorr. Thc secoad crprcltor, used to raooth the ractlfled RF rayeforE, ls locltrd !t thc tcralDrls of r 1rA FSD DC oilllameger. Thc Ecter can bG located lcDotcly, lf dcclrcd. Usc ghleldcd cabl. betsce! the curreat probc aod th. retcr. ltc dlodes rre gcncral purpoae gernalnluD types. Th€ E-core i8 r 8p.chl lten (rubstltutr.oDr are caally uede), avatlabll frou Anldoa Assocleies, 12033 Otr.8o Strcet, llorth Hollyrood, CA 91607. Orde! prlt auaber EA-77-lggi lt lacludca r lylou bobbla.

A. rlth aay rcelurlrg devlcc, thc rmcter uurt be crltbrutcd. Ttrc 500-ohn pot la edJustcd for tbc deslred rcrdhg uhllc e kaoy! Rp surrcnt la peescd through "lcnom tbc prlury. Thc R! currentrr .lght bc the output of a oeter crllbratloa lource, l raodou altcDra curreot clnulteneously uooltorcd by en R! .lrctcr of koom callbratloo, ot a kqom Rp voltrgc and loed rerlctance. If moe of thcsc are tvalleblc, clllbratc thc tu.tcr rt [latscalc rlth your oro p.rtlcular aDtraDr current, yhltcver thlt llght bG. ThG oeter crD thea be aorltored for cheagea 1! tDtenDa curr.at. Evea though the currcDt lc unkaoru, tou cra rtllr rttch for relatlve chauger rheq varlous trtlrolttcr, antaDna, or grourd lEproveoents rrr udr. Be lure to ldjurt for coactant poycr, "lnproveneata'r lnput otbcrs{rc rlght be thc !e3ult of loedhg changca.

TbG asllert place to Delaure roteuaa currelt ls et the botto[ of the loedlag coll, but thl! lg not the true lDtena! curreut. Thc coll rlII exhlblt aone caprcl.tance to grouud aod that rlll shuat ayry loEe of the curreat before lt raachca thc aotelaa. Aoothet uethod lr to pl.rce the Ectlr rt thc top of the loedlng coll, or at the base of the rateona. Horevlr, crutlon oust be cxcercLecd. Thls ls a voltage aode tDd sttlrf crpacttlnce contrlbutrd by the )J

lcicr lud RF curr.ot probc rlll rhuat ro[c rotctu currrat rre]r, th.rcby dccr..ll.g thG .ctu.l 't.!u eurrent. rf !h. act.r lr rttrch.d iircctty to tbc voltrge aodc, r lull lGtar oovcocnt ahould bc uscd rtg,ht rt thc curraat probc llDlolz. -to rtny crptcttrnc.. r[ tht.! c.s. Do Nor locrtc thc rcter tcrotcly rr prcvlourly sugge!tGd.

TbLr currcat probc urcs a tuall E-cor6 ,o thrt lt een bc clengcd oo to thc rEtcaor !)r.t!8 ro vrrr,ou! plrccr rlthout htcrruptrDg thc crriult. rt ceu :vca bc chnpcd oD to groutd radlek to gct cotrprr.tlve r..dlDg! of rrdhl .fflcl.hcy. Lergcr E-corar or toroldr crB bc rubrtttut.d clth llttl. ot no cffrct ou thc clreul.t vrluar lhom. An tpproprhtc torold for ectually thrardlag ovor thc rnt.a!. lrrt ltrclf l! a;-rr-240-77, ulth r 1.4,, lnrldc dlr!ct.r.

If ra E-corc lr ueed er e clrop oE laDetcr, bc cereful to aot chlp thc Drtllg feccr of ceeh hrlf. Uhllc thc currcnt irobc lr raletlvcly taccucltl.vc to .llgBD.at, lt ls dtraocty lcDllttvc to lDrll gepr cturcd by dtrt or durt trlpped brtr..D th. lrttEg frccr. Thc tso helvca ol thc EA-77:1gg cea bc hcrd togcth"r by r rubber bend or cloth.lpla.

AI'S'Er.wA

€A- 7"-rtg

25 ruors cbr 3OBBt^J ,oo.+ G"

fuu--t

RF AINTI,T--'€R. COrV1PON€F.JIS CAFJ BE IflcdNcD on FAcK oF fngrE.R , f{+

LF DIPPER AND RESONANCE CHECKER by Dav id Johnstan

This is a DIP natcr I havo ugcd for sbout a yaar now with 8.cat guccegg. I hava uscd it to chcek resonant frequoncy of my VLF antenna sith no loading coil (just tophat.adialE), to check rcsonanco of thc antenna pith the loading aoil in placc, to check rcsonance of thc loading coil it:'el,f, and to check tuned eircui!s yhcn building transmi.tt6rs and convcrters. Thig inst.umant givcs a nicc sharp dip et rasonant fFcquonay, thc dopth of thc null dcPcndind on thc Q of thc circuit undcn test, Nonmally a two turn link from the dipper wound around thc coil undcr test givcs a nica pronounccd di,p Fith littlc laading offect.

l'lost of th6 parts used are not cspectally critical. Lots of junk box pa.t€ wora uscd in th. prototypc. L1, C! and C2 arc ctragen to ragonate over the band of frequonci,€s desircd. As a bandspraad cap I havc ugcd a broadaest band 25 to 865 pF variablc for C1. C2 is a 68OpF fixed capacitar. This givos oa a tuninE rengc of 156 to 27A kKz. A Eeitch can bc added to changc values of caPacitors to rai€ta or Iower th6 tuning ranEle. If you add Dorc capecitancc, yau will be able to tuna lorar in frequcncy, but yoqr hi,gh frequcncy and wil.l bo lowcred accordingly.

L1 iE approxi.Datcdly 1MH. (a ni I lcr 9015 coi I with one Dic rcnovcd).

t'11 can bq any gcnsitivc Dctcr you hava lying around, thc Dor6 Ecngitivo tha Detor the mor6 pronounced the dip wilt be. My prototyPo usaE a lO0 oicroa[p Dovcocnt with good Eucccss. A I oe DavcDcnt could probably ba ugcd sith a transistor Deter aoplificr.

I uscd a 4 turn link eround L1 .qnning onc sid€ to ground and th€ othar cnd out to a tcrninal. This is rhcre the high side of th€ link going to thc cirauit undar tcgt ig connactad. Thc othor Eide of that ltnk is connoctcd to a graund tcrDinal on the rsgr of tho chasgig.

gcrvcs gignal This unil algo 8s a ecncrator in tha LF rangc. I hava anothe. terDinal (JZ) on thc rcar of tha chagsis into rhich I connect a frcqucncy coqntcr for vcry accurato r€adout. t'lost of thc ti.Da my calibretcd front dial Earks niaely.

I ao an cI€ctronicg instru€tor at ITT Technical Ingtituta, -Etqdent and, as I tol I my class, this cirouit is proof-. Yoq raally havc to try for it not to [ork. 55

9 H 0A D,q,vEror ^rs r-e,:t 5-.s3ote E-F_6-E:E"ETT--T-Sb- -eEs-fftqE-cE eHEcKEq:

JJ

I I I _= r'

rAKt> Ll-r RL - 22 Ohn, 1/4w CI - 25 to 365 pF variable R2 - 7 K, r/4v C2 - 640 pF R3 - IOOK, l/4w C3, C4 - .47uF R4 - 22O Ohn. I/4w Jl, J2, J3 - any type EXCEPT SO239 Ll - around I mH (scc toxt) L2 (link) - A fev turns around Ll. Q1 - nPF 102, 2N4418, ctc - t41 1OO uA or whatcvcr .iunkbox has.

S@11. teipor.rt Lj.nk bets€en ancenn! b6sc aod gi-und.

Cheklng rasonance of ilsT'i"::::":ff:"::l75O !{ l6dcd antennd *::fi:"i::"H;:.* 'H'lr:ll;i"::";;"i'3l3lio"::li: nub* or turtrs(2 or i shourd

TYistcd vire Tunad clrcult (l0I cd) under te3t. 5b

ONE OOZEN].?50 IIETER TRANSMITIING ANIENNAS LJCUo#Sp3

^18r

/.

A- 26 ft tubuLar steeL verticaL. Reference ant- 6db. Jurt distinquishable at TYp, 120 diles. 8- 50 ft ssperded veDtical, RG58 U, center and blaid ti.ed together. +5 db, 120 ni rtLn C- 26 ft vertical uith 24 ft section. +2db at 120 mi, +6db in nea! fieLd (I/a mi). "Tn. 0- 26 ft verticaL uith t@ 24 ft top hat srctions for +6 db at I20 ni. E- J5 ft sspsded uire cage, 4 uires forming I ft squale a! t@, sth uire runs d@n the cente!, all uiles rcting 6 ft above feedpoint. +8 db at IZ0 oi. F- J6 ft ster mst supporting 4 uire cage, rigid support Erbels at top fom 16 ft sqrare. cage uires g cmnect to mst at ft. + 1,0 db at I20 mi. A structutal nightoare- not rsmended. nEgEbeatern G- uire cage suspsded frm and attached to J6 ft steer mst, guys tensioning the cage errents' (mre guys needed to support rest) +8 cb at 120 nires. could be vely oood uith rcre cage uires. H- Susperded five uire flattop uith 5 dounleads neeting I ft above feedpoint. Height-is ft, each tophat sti.m 15 ft, tophat ul.dth I ft. + 12 6 at I20 mi. All of the above antemas uere el4led in quick pEoglession at fiy Zebla 1 sitet fa! field evaluation uas done by tl€ late Art Chlldr TYP. I- 6 ft vertical uith 3 el,mnt asymetlical tophat of 44 ft. Hi.gh cl,ear location over a good ground plane. -3 db but leadily copyable at 60 miles. J- 30 ft velticaL uith L2 16 ft tophat erments and J cage d@nleads meeting mast at about L2 ft. ToPhat eL@nts srculed to fenceposts. Approx +13 to +15 db, hard to tel,l as this antenna is in superior location and has far better ground (150 radiars, 20 gnd rods) than any above except I. K- 30 ft ilspended uire veltica] uith I 20 ft tophat elments. Performs ruch tike J above but because it is located at my canyon-bottm hme it is rcre than 20 db belou J in lar field. nantennarr L- UMerground Transmitter output goes through filter and natching transforme! T. Transformer tap and parallel capacitance C are sel,ected for maxiM curlent reasuled at RF meter f'l. The coax is buried and luns about 200ft to a rmte ground systm. Probabl,y 24 db belou J but it has been cogied at 33 miles. tila stna.rt r! t/}r, ?olci nu, flaFrl ?rtrr o.{. )li.i L0Nqh/AVE)Grre AERTALs t60 - tqo tsg aeaf- f ta, j L- v3 ro'r l' ?r-(. retE|ocrs. Fi€A USrr(y Ff?gttiierJr*t lJ)at2.unsr'lDa{rtr 1tlriL 13:Fi^("t. I Aail.t. RAD.a 7r' ' laco 'LrcgNt?'fta€'aAYD i'tturrc J.,utC- ,tl(! l.r3 lla|,"c?rre?Jc orra r^lt'? to Fr- r!T. ,tart ,!Ar. r-(crt;ltl orl r,ei rer) N.TES: 1-Ys 8 FI Ll ^ G):f;ifJt: f,^o.rrs.!ro? 7( 8 &irrte^ol t||, drr€, r| "f |tisi,.tr aar..tfl H, Sorr'rwtr,.ltr THUI v to 9-ttrr, a3 tgiat,t&iD rt ltla5 Aaaf^j Afaltt s.t L'J caotert.t At rr.Eatas llr::,:*,"""k caat,Jot t{r ?tttrac ,a.J. A tT wF|.rfi iale'(. talo o; !'-#i w Aut'tlitctr+ Aat€,, tra t' F19 ( Lfc -lraf,*oa-F *tPnoprr*te t9se,n,et aT (9 5- tot rr? r,,.,n,ls X. Strtf- f ctt a' tett)E ,fz tttE, J lftcrrlrr F:lr BCEI ao 6uyf g ! ro rrrrrs/- o / ll8 To. lSD na. / srt5 trrcat+r5l t |rtrc.t!E"l.rr. 5 ai,Drci*r39 .' \Ll - l.trah-\ -l- J trxatart Ug e mrr 3? 56 Ft: i l2,O ,t aa tv ,rJt a-l \ Lr - l.'nh 5 ,I /Lt- l0xa. Lg . f.7 tl.\ AO'.C?LC For.G/lllt Lg c curt?f b ,rto tt'\- li tL{aTrrr?! nt !: ttrq ,7ttrt!g t | 7lzur,jtrt&.' e-slt r ,ritr s.

PcoR Grr- YCA(. LorG 7 n*D/dlt.4.5oft 6LL +GtrrrD st*xE. Mogarr/}ttl,ToP tbtlJ €Q,otrtr> +3.r{l J7 Pr*,ue.t.- .5orr. + 6alr.tD tl}Ke \ n/az PLqt Lctrc <6ub'tct?.rJe tte€ f ttrg'rYt. *w6r1f f 5B

EverythingYou May WantTo Know About Litz Wire ...But Might Never Have Asked.

'litz l-l-l hc rcrm wirc- rcfen to a typc of mnductor cight prctwisted cables of five strands each or four of tcn I pcculiar ro thc €lcctronic coil indutry. Its multi- strands. l- strand construction of srnall gauge, precision Evcn in a properly trristed lilz cable there is still some t*isrcd, film insulatcd wirc minimizes thc powcr losscs re- skin cffccl. This is due to thc finite size of the strands latcd to thc'skin cffeci" ofclrrent at radio frcquencies. thcmclvcs, cach having an appreciable skin cffcct at high Thc skia cffca of RF currcnt in a solid conductor is its frcqucncics. Thcrefore, a litz conduclor made with many conccntration in a thin layer at thc periphcry. Thc effect strands of very fine gauge wire can be expected to pro- rcsults from thc intcmal and cxternal distribution of flu ducc higbcr Q coils than molher equal in arca but having lincs. If thc solid conductor is assucd to b€ madc up of larger and fcwcr strands. a numbcr of clemcnts in parallel, thcn thosc in the in- Thc mcthods used by Kenigan kwis to fabricatc litz tcrior, surroundcd by morc flu lincs, will havc grcatcr cablcs arc complctely in accord with the abovc theory and rractanoc: hcncc lcss currcnt will flow in these clcmcnts rcasoning. Standardized fabricating praedures, designed than in rhosc in the extcrior. As a result thc sncnt is to cffect precision strand transposition, are closely fol- crowded to thc surfacc or skin of thc conductor. lowcd. Conductors having fcw strands arc formed in a Thc abovc analogy can bc translatcd into reality if one single twisting opcmtion, multi-strand cables are built up substitutcs parallcl, but insulatcd, strands for thc imagi- from twistcd submultiplcs in onc or more succeeding op- nary elcBcnts dcscribed. In this instancc, and for the crations. Thc cables thus fabricated are soft and free from rcasons givcn, thc strands at thc corc will carry littlc or no work hardcning and springincs. Most important, an un- clrrcnt: rathcr, most of it will bc conccntrated in the uually high degrec of spool-to spool and lot-to lor unifor- outcr slin of thc wircs on thc surfacc of thc parallcl- mity is thercby attained. strand bundlc. Such a cablc construction frequcntly has Polyurcthanc film insulatcd wire is nrost commonly only slightly less RF rcsistancc than an equivalent arca uscd for tbc eblc strands because of ils low electrical rclid conductor. losses and slderability. Strand gaugesusually range from Howcvcr, if a rclatively fcw insulated stmnds arc #30 through #50, and the numbcr of strands, from as few twistcd together in a prccision pattcrn and with a prccise as three to as many as a thousand. Thc litz cables are av- minimum lay, thc thcorcticd rcquircmcnts of a high fre- ailablc with convcntional singlc and double seruings of qucncy conductor arc mct. With such twisting cach strand tcflon, cclanesc or nylon, singlc nylon space-wapped in thc conductor occupies corrcsponding positions in thc scrvings, and unsewcd. cable for cqual distanccs; thcse positions ranging uni- Therc arc no Amerien military or wire industry formly from the ccntcr outwild to thc pcriphcry and rc- specifications for litz wire. In their absence, Kenigan tum. Thc strands will thus carry cqual crrrrcnts, for cach I-ewis closcly follows its own long establishedmanufaqur- b swoundcd by thc samc amount of flu pcr unit length. ing practices. Thc eblcs arc fabricated as described Equal trasposition of a gcat many strmds is impossi- abovc and, when conventional rcwings are applicd, their blc to accomplish in a singlc twistng opcration. Accord- builds approximatc thosc of magnet wirc. Thc ingly, thesc eblcs arc mdc by twisting togcthcr scvcral polyurethanc insulated wire from which litz is mst com- prcviously twistcd componcnt cablcs. For cxamplc, a monly made conforms to specifietions MIL-W-583 and forty-strand cable might bc madc by twisting togcrher MWz. ITERN,IGAN.I,EUIS WIN^E PRODUCTf| 4421 W. Rice Str€et . Chicago, lL 60651 . (312) 772-7209 59

FCC RULES AND REGULATIONS ( Abridged )

S l5.lll ODcr.aion bclor IGOOtEa A loF porer cooEunlcatloo deyle oa, be operrtcd o! ant ft€quelct b€tFe! lO rtd {m kII! or b€twe! 510 rnd 1000 kHz luhrect to th. @ldlilon tblt tbe @tslo! ol RF e!€!!y ot the tudtD.lttl trequelc, or uy hlEoDlc o! ot_ber lpurlou lFqueDc, d@ lot c&€d ti. leld streEat! h th. tolloPbt tlbtq

4O ;as; g.@ ;E;;

!l5.ll2 lltcmrtivc proviaionr for opctetion bcarel 160ud I90 k8a

In U.u ot oeth! tbe FqrdnEeot! o! | 1i.U1, r lor goraa @EEonlqdo! deile Ery otErata o! a!, ft.qqeDst lD thr bud 100-lgo lE! prortd€d lt Eet! dl t!. loUorlaf @Ddldoul (r) TD. !pr.r bput to thc ilrl ndto lrqolDq (ctdEdya rtrt! ol trLEeDt or hcttar tFwar) dq Dot crced ota rltt (b) AU ElstoDr balow 100 kE, ot lbovr 1m tqz E $ppt€rd m dB biloE thc uEodulrt.d orrte!.

tc) The totrl le!8th o( the tttsEbsto! lbe ptu thc rlteDu de! oot er|s l5 Eetcr.

!l!.Ul Catiietlor r.qrircd tor dGtico ahd r !Dl.a.a c boilt h r qqutttt tuar! thr. 5 ud ma utd.a (t) A lor lbrcr @EE[alqdo! davle ErDqtte tutrd b.tra Dccleb.r 31, 106? ud Oc!ob.. L 19t! rhlcb tr Eetct.d or rblcb t! bullt h r qnodo tutc tiu 6 ud oot ruLct.d, !b.lt bc eltcttl!- €trd pu@t to tlc DF l.lou o( ll 15.l36-15.ilt4 (b) A lor porcr oooonletlo! dctla Ernotls tuFd dtr! Ocbb.r l" lgt6 rblch t Erllltad or bultt la I quBtlt' tF.br thD 6 ud rot D.rtctcd .bru b. g[b9.rt ardlctcd IEmrDt to B ol tht! Dd,

! ls.llt Cdiiiqtlo! rd idotliotlo! rcqdrd (or L6. bEilt daie

A p.M rL! @Btmt! lot en tbt! iE lot tFRt sEEsdodoD darlg for h! on @, ud Dt lor rlq lGGd loa D..t tb. rrqslraatr ol | 15.131

rnd | 16.1&L h llc! th..et, h. rb.ll rttlcb to 6eb !fth dcvlc r slF.d rDd drt.d ltbel th.t r.d! u lollon: I Drra olalroctd tib d.rte to? [t on o&. I iar. t6t.d lt.Dd antrt tur lt sEDlld rli! l!. rpDllobb frSl.tb.. oa POC 8016 Prrt 16. 1opt oa Dt E{!r} EarC tr lo Et F.6doo ud l. rvrurol. for bFtb!.

(Drt.) 60

ARrI J 'vwtt$Jt#-ffi'5i . ltp ,.",*nrq h6 otre6r trv' *oms rhat o^o yery nrcs t0 salvsff [Filtd|m sef.rtc8. itB reottriu imi]ioiir"t wfriot m0r8r,0r)rso rof-rGs. morte eith€r cer€rntc r oniomtrton "lr;*'"{rp_,ouoore;riiiriii'iiirmcr;t aril;te,-'6'r*i i.iiutr"rry l6t6 wo',to rqrte htoh rmrcrtnco-Riihdd'1" ilii3.i'o,orr IheARI t3's it oqo"* ororher structuro. TT9F.pr.r "ilbd, ;td; $runrwhtch onovrs 6 S dnp futt scllo rdrns wnhuB $unr remold,.up merd-irfi iio ii rrri;i;: mncnont)fierolV or€serve"thetr ifr'r&';rlJto"bw oa b000t0rnd caltOritmiitti tiie^$,unt,sofoirly @rrate reodtngs mr,/ bvdrvrd'' rl' numbersm *re crairre.- -' iil nit "t ;i* bywbriil;;6dio hlo...mrgllko lS0to 200 m0 at full scate. .a

srAp[EsT AORE FLFXIALE

/4ATEHING TRANSFOR'{TRs

GRoUNOFo( UNBALANCED / INPUT OUTPUT

FERRITEIJATSIII{C IMNSFOR}18R5 ,- _, .l_tqpd motqtingtrilsform€r. betwen trdEmitter (r filter) ortputild the iltenno lgrL{ rqfgp cdr b80 r6t cmv€ntsncs.Ihts ts pructlrv tr's when(lsi$ fetfs dtctoto ulotUE flllput.stw s88sflne sp€clflc lod impo&nc8.IiE matdtinglrilsformer ii olo involuoble rr expeflmonurtimwtth cqJntefpolsos, boloaEed 6ntenn6 dE ttE like. ( .Use_afoirly lrg 1.5' r. bipr) tq-oidof hig permedilityfemite msteriol. Wr@ ths qTewilhriberglqrtopo.wrndwith'rBrrmvierenoineiedwire.0.v",*rselitz,uuttiliii mt relv ossfittclslrf,s mV a lltue blt of wtrs ls n€ft. _-..?*ul.gl1lryI0_t]9ls^tropcstble._f,tyfororiteemglo/sm ir*penenr l0 turn primory un 0 z) l0 50 turnsmfihry, tepd 8v€ry3 0r 4 turns.Boltrtc€d or unbslonced16 canb; driv; IrlLJl,rsfflry.nqtr. Must fr mo(imumdrtput ild minimumDC sr.rpgly cument. r-eJ.'.lgr-?q-rgslllr rmprwrngwften)& st to thet6t tEp,ert'r buirda wicbr range rransformer 0r mcEttytfE cnorctefl$tcs or vurr tm. 5d bz"+d Qd ltrx Crrtrr, t *rmtllnd, IY g2Fl