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Transmitting Antennas and Ground Systems for 1750 Meters

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Transmitting Antennas and Ground Systems for 1750 Meters 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 .
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