DOCSLIB.ORG

ANTENNA COMPENDIUM the ARRL Antenna Compendium Volume 2

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
ANTENNA COMPENDIUM the ARRL Antenna Compendium Volume 2 \THE $12°° ? D\ ANTENNA COMPENDIUM The ARRL Antenna Compendium Volume 2 Editor Gerald L. (Jerry) Hall, K1TD Assistant Editors Rod Gray, WA1DVU Randy Henderson, W15W Charles L. Hutchinson, K8CH Joel P. Kleinman, N1BKE Production Leslie Bartoloth, KA1MJP Michelle Chrisjohn, WB1ENT Sandra Damato Jacqueline Hernandez Jodi Morin, KA1JPA Steffie Nelson, KA1IFB David Pingree Dianna Roy Hilary Vose Jean Wilson Cover Design Sue Fagan The Cover Theme: Radio signals propagate from the antenna, through the ionosphere, and to distant points on the globe. Sometimes the ionosphere displays visible phenomena, as discussed in the final paper of this volume. Feature photo: Aurora australis. Taken south of New Zealand looking toward Antarctica, by Col Robert Overmyer from Spacelab III (Challenger). The principal investigators on the Spacelab III auroral project were Dr. Thomas Hallinan and mission specialist Don Lind. The photo shows not only cloud layers, but also the airglow layer, stars, and the aurora. (NASA photo) Inset photo: Aurora borealis, showing the entire auroral oval. Taken September 1981 from a spacecraft altitude of approximately 12,962 miles. The sun illuminates the earth from the left-hand side of the picture. (NASA photo) Copyright © 1989 by The American Radio Relay League, Inc. This work is Publication No. 112 of the Radio Amateur's Library. DUblished bv the Leaaue. Printed in USA $12.00 in the USA 1st Edition Second printing, 1990 ISBN: 0-87259-254-5 Foreword In 1985 the ARRL added The ARRL Antenna Compendium, Volume 1 to its library of publications. That book contains 176 pages of previously unpublished material, covering a wide range of antenna types and related topics. The foreword of Volume 1 suggests that Volume 2 of The Compendium might logically follow. Like its predecessor, Volume 2 contains all brand-new material. Because antennas are a topic of great interest among radio amateurs, ARRL Headquarters continues to receive many more papers on the subject than can possibly be published as articles in the League's journal, QST. So again, as with Volume 1, those papers have been collected here and combined with solicited material. None of this material has appeared in print before. Whether you have only a casual interest in antenna construction or a serious interest in understanding fundamental antenna theory, you'll most likely find something to stimulate your thinking. Will a companion Volume 3 appear in the future? Very likely. Amateurs' interest in antennas never ends. David Sumner, K1ZZ Executive Vice President Newington, Connecticut September 1989 Diskette Availability Six papers in this book contain listings of BASIC programs suitable for use with an IBM PC or compatible computer. Some papers include more than one program listing. The programs aid in performing various design tasks associated with antennas, as described in those six papers. The ARRL offers a 51A-inch (360K) computer diskette for the IBM PC as an optional supplement to this volume. The diskette contains 11 BASIC programs in ASCII text format, and one compiled Pascal program allowing a more extensive series of calculations than its corresponding BASIC counterpart. The diskette is copyrighted but not copy protected. The program files have been supplied by the authors of corresponding papers, and filenames have been assigned to resemble the authors' last names. The diskette is made available as a convenience to the purchaser. The ARRL has verified that the programs run properly, but does not warrant program operation or the results of any calculations. Contents Vertical and Inverted L Antenna Systems 2 Vertical Antennas: New Design and Construction Data Archibald C. Doty, Jr, K8CFU, John A. Frey, W3ESU, and Harry J. Mills, K4HU What length should a 1/4-X vertical radiator be for resonance? More than likely it is not 234/f(MHz). Capacitive bottom loading? Folded monopoles? Data from extensive tests are summarized in this comprehensive paper. 10 Steerable Arrays for the Low Bands Bob Alexander, W5AH You can aim your beam electronically with time-delay beam steering. The beauty of this system is the steering angle is independent of frequency. Use multiband radiators for beam steering on different bands. 16 A Steerable Array of Verticals S. L. Seaton, K40R This array covers the 40,20 and 15-meter bands. On 40 meters you can steer the beam in four directions. Band changing and beam steering are done without a complicated relay system, using a simple manual method to switch base loading coils. 19 The Robert Tail—A DX Antenna Robert L. Brewster, W8HSK Invert a bobtail curtain, feed it with coax, and you have an array that reaches out and grabs DX. Nest one inside another for 80- and 75-meter coverage. 25 The Simplest Phased Array Feed System... That Works Roy Lewallen, W7EL Feeding two array elements from a T connector with lines that differ electrically by 1A X will probably not give you 90° element phasing. Why not, and how you can get the proper phasing is explained here. 36 Unipole Antennas—Theory and Practical Applications Ron Nott, K5YNR Unipole antennas are sometimes likened to gamma-matched or shunt-fed antennas. Are they the same? A properly designed folded unipole is superior in some ways. 39 Magnetic Radiators—Low Profile Paired Verticals for HF Russell E. Prack, K5RP Would you believe you can have an efficient HF vertical system without radials? And it need be only a small fraction of a wavelength high! 42 A Multiband Loaded Counterpoise for Vertical Antennas H. L. Ley, Jr, N3CDR There's been a lot of talk about using lumped loading in a counterpoise system of radials. Here are the results of experiments doing just that, with information included for you to build your own system. 46 A Multiband Groundplane for 80-10 Meters Richard C. Jaeger, K4IQJ If lumped loading of counterpoise radials works, then why not use traps instead? And with a multiband radiator, you end up with a multiband groundplane antenna. 50 Tunable Vertical Antenna for Amateur Use Kenneth L. Heitner, WB4AKK/AFA2PB You can feed a vertical antenna with an omega match. And with this arrangement you can change bands with a relay. A simple remote tuner gives you the final touch—the ability to QSY up and down the band but yet adjust for a low SWR. 52 A 5/8-Wave VHF Antenna Don Norman, AF8B For either permanent or temporary mounting, this antenna accounts well for itself. The location of the ground-plane radials is optimized for minimum antenna current on the transmission line. 54 Some Experiments with HF and MF 5/8-Wave Antennas Doug DeMaw, W1FB A 5/8-wave vertically polarized antenna is a winner on 160 meters! Install it as an inverted L. Yagi-Type Beam Antennas 58 New Techniques for Rotary Beam Construction G. A. -Dick" Bird, G4ZU/F6IDC Rotatable beam antennas don't always require aluminum tubing, nor do they need a large turning radius for reasonable gain and F/B ratio. Use these techniques to construct inexpensive beams. 61 The Attic Tri-Bander Antenna Kirk Kleinschmidt, NT0Z Efficient Yagi beams can be made of wire. This indoor Yagi antenna covers three HF bands! 64 Yagi Beam Pattern-Design Factors Paul D. Frelich, W1EC0 Over the years, antenna theorists frequently calculated complex radiation patterns for multielement systems by combining array patterns. They considered the overall antenna as an array of arrays. Couple this concept with the ability of a computer, and you have a truly powerful analysis tool. Quad and Loop Antennas 88 Half-Loop Antennas Bob Alexander, W5AH Half of a full-wave loop antenna can exist as wire in an inverted-U or inverted-V shape above ground. The other antenna half then exists as an image in the ground and radial system. Such an antenna offers quite respectable performance. 90 Coil Shortened Quads—A Half-Size Example on 40 Meters Kris Merschrod, KA20IGfTI2 Try a quad with electrically lengthened elements. This paper tells you how to design them, and includes information on using a computer in the design work. Multiband and Broadband Antenna Systems 96 A 14-30 MHz LPDA for Limited Space Fred Scholz, K6BXI You can cover 10, 12, 15, 17 and 20 meters with this rotatable array. Being mostly wire, it weighs little and has low wind resistance. It's just the ticket if you live on a small city lot. It's great for portable use, too. 100 Antenna Trap Design Using a Home Computer Larry V. East, W1HUE You can make traps for multiband antennas from nothing but lengths of coaxial cable. But how much coax, and wound in what coil dimensions? Avoid the tedium of cut-and-try designs with this simple computer program. 103 The Suburban Multibander Charles A. Lofgren, W6JJZ A single antenna covers the 80- through 10-meter bands. Although the design resembles the G5RV antenna, its lineage and operation are different. 106 Fat Dipoles Robert C. Wilson Mention a "cage" dipole and you immediately have a hot conversational topic. This simplified technique offers some advantages of a cage dipole with a lot less wire. 108 Swallow Tail Antenna Tuner Dave Guimont, WB6LLO This unique adaptation of a fan dipole lets you remotely tune the antenna for 75 or 80 meters by mechanical means. It covers 40 meters, too. 110 The Coaxial Resonator Match Frank Witt, AI1H If you use a dipole on 80 meters, you'd really like to feed it with coax and have an SWR below 2:1 across the entire 80-meter band. Recent ideas have met with success. This one uses a unique combination of coax sections as resonators. 119 A Simple, Broadband 80-Meter Dipole Antenna Reed E.
Load more

Recommended publications
  • MFJ-16010 Random Wire Antenna Tuner Thank You for Purchasing the MFJ-16010 Random Wire Antenna Tuner
    MFJ-16010 Random Wire Antenna Tuner Thank you for purchasing the MFJ-16010 Random Wire Antenna Tuner. GENERAL INFORMATION The MFJ-16010 is a variable L-network designed to match the low output impedance of your transmitter to the high impedance of a random wire (or vice versa). It will match almost any random length of wire to any transmitter from 160 thru 10 meters. The transmitter may have an output RF power up to 200 watts. For best results, the random wire should be as long, high, and clear of surrounding objects as possible. Do not ground the random wire antenna. The connectors are labeled properly to match a transmitter to a higher impedance. This is the normal connection. To match impedances that are lower than your transmitter impedance (such as a mobile whip), simply interchange the normal transmitter and antenna connections to the MFJ-16010. Remember the MFJ-16010 is designed to match a single random wire and not a coaxial line, even though coaxial connectors are used for both antenna and transmitter connections (these connectors make it easy to interchange antenna and transmitter connections). A standard banana plug will fit nicely into the center of the S0-239 coaxial connector and can be used to connect the single random wire in lieu of a coaxial plug (PL-239). A standard coaxial cable having an impedance that matches your transmitter output impedance, should be used to connect your transmitter to the MFJ16010. Make sure the MFJ-16010 is well grounded to the transmitter. If you are using the MFJ-16010 to match a vertical or mobile whip, the tuner needs to be at the feed point of the antenna and not at the transmitter end of the coaxial transmission line.
    [Show full text]
  • Which HF Antenna Should I Get?
    Brass Tacks An in-depth look at a radio-related topic Which HF antenna should I get? You’ve earned your General class license, and now you’re thinking of entering the wide world of HF (high frequency), which is ironically low frequency com- pared with much of the remaining amateur realm. Af- ter posting controversial questions on Facebook, you’ve finally decided on a very pretty, feature-rich HF rig, one that’s supposed to deliver 100 watts to the airwaves, and maybe includes a built-in tuner. Being the educated ham you are, you already know what coaxial cable to pur- chase, and maybe even the connectors you’re going to need. But that education has also taught you that you now face the most important question of all: which antenna? The decision about your HF antenna choice is not a trivial one. Some things to consider include home space restrictions, aesthet- ics (whether it looks nice with your home), and price. Ok, if money was no object, let’s go straight for the jugular, shall we? You want a 200-foot Rohn tower, a Yaesu rotator system, Cushcraft X7 beam antenna, with the X-740 add-on, all connected by Heliax. Well, you can dream, right? In reality, you live under the thumb of an HOA, your spouse will gladly allow an invisible antenna, and you only have $59 to spend on it. So, the goal is to get into HF ter- ritory within the limits specified by our environment. Not always easy, so let’s break this down, and then arm you with the infor- mation you need to make an informed decision about where to go next.
    [Show full text]
  • Antenna Articles Collection of Short Articles Relating to All Manners of Antennas
    Antenna Tips page 1 of 31 Source : http://www.funet.fi/pub/dx/text/antennas/antinfo.txt Antenna Articles Collection of short articles relating to all manners of antennas. These articles are the hard work of Wayne Sarosi KB4YLY (995 Alabama Street, Titusville, FL 32796) SUBJECT: Circular Polarized Antenna There has been a request for a series on 'CP' antennas. The term 'CP' eluded me at first as I was not familar with the abriviated designator for circular polarization. At work, we just use the entire words. I'm going to begin this ten part series with the basics. After researching CP designs with a few engineers and fellow hams, I found that they knew very little about the subject. I also found I didn't know quite as much as I thought I did about circular polarization. So starting at the begining will help all out. First, let's discuss the circular polarized wave. There seems to be conflicting standards used by the world of physics and the IEEE. I found this to be true in four reference manuals including the ARRL Antenna Handbook. At least it's stated right up front but biased according to which text you read. We will follow the IEEE/ARRL standard in the following series for obvious reasons. There are two types of circular polarization; right and left. All of us agree up to this point. According to the ARRL Antenna Handbook, the following statement: 'Polarization Sense is a critical factor, especially in EME work or if the satellite uses a circular polarized antenna.
    [Show full text]
  • MFJ 2004 Ham Buyers Guide
    QSTCatP01.qxd 10/16/2003 10:03 AM Page 1 MFJ 2004 Ham Buyers Guide See inside for these New MFJ Products! 300W Automatic Tuner Tiny Travel Tuner DC Multi-Outlet Strips Ultra-fast, 2000 memories, antenna Fits in the palm of your hand! 150 has both 5-way binding posts switch, 4:1 balun, Cross-Needle and Watts, 80-10 Meters, Bypass Switch and Digital SWR/Wattmeter, 1.8-30 MHz Anderson PowerPole® connectors MFJ-902 $7995 $ 95 MFJ-1129 $ 95 109 MFJ-993 259 Four New models -- balun, Four new high current 150, 300, 600 Watt models. SWR/Wattmeter . DC multi-outlet strips . See Back Cover See Page 6 See Page 16 Balanced Line Dummy Load Manual Mic/Radio Switch Antenna Tuner SWR/Wattmeter Screwdriver Switch any 2 mics 1.5kW, to any 2 rigs Superb Antenna peak reading Covers 40-2 Meters balance, switchable 1.8-54 MHz, to external MFJ-1662 $ 95 $ 95 300 Watts antenna 129 MFJ-1263 99 $ 95 $ 95 MFJ-974H 189 MFJ-267 149 Four new models . Three new models . See Page 7 See Page 9 See Page 42 See Page 21 10 foot Antenna 160-6 Meter 1.5 kW 4:1 Glazed 4 Foot Telescopic Tripod Doublet current balun ceramic Ground Whip 40-inch Antenna /insulator insulator Rod MFJ-1954 between legs Copper bonded steel MFJ- $ 95 MFJ-1918 MFJ-919 MFJ-16C01 MFJ-1934 19 1777 $ 95 $ 95 $ 95 59 $ 95 3 lengths . 39 49 69c 4 See Page 42 See Page 42 See Page 43 See Page 43 See Page 43 See Page 7 Mobile Discone Atomic Atomic Wireless Speaker/Mic Antennas Antenna 24/12 Clock 24/12 Watch Weather for Yaesu VX-7R MFJ-1456, $14995 25-1300 Station MHz 40/20/15/10/6/2M MFJ- MFJ- MFJ-295R $ 95 $ 95 MFJ-1868 132RC 186RC MFJ-192 MFJ-1438, 99 $ 95 19 10/6/2M/440 MHz $5995 $1495 $2995 59 See Page 41, 39 See Page 40 See Page 29 See Page 30 See Page 30 See Page 35 Ameritron Ameritron Ameritron Hy-Gain Screwdriver Digital Screwdriver flat Mobile 80-10 M Vertical Antenna Antenna Controller SWR/Wattmeter The Classic is Back! 5 1.2 kW, Pittman Super bright high- Just 1 /8” thick, AV-18AVQII Commercial Gear Motor intensity LEDs flat mounts on $ 95 dashboard 229 SDA-100 SDC-100 MK-80, $79.95.
    [Show full text]
  • Long Wire Antenna
    ANTENNA AND WAVE PROPAGATION Long Wire Antenna Long wire or random wire antennas are very simple antennas. They can come close to half wave antennas in efficiency, although efficiency decreases as they are made very long or installed closer to earth. Technically a true "longwire" needs to be at least one wavelength long, but Hams commonly call any endfed wire a longwire or random wire antenna. Advantages & Disadvantages The antenna itself works just as well as any other wire of similar height and length. Any or all problems are in the counterpoise and feed system. The difficult problems associated with random wire or longwire antennas are caused by ground currents and radiation from the single wire feeder. Endfed antennas, or antennas with the single wire feeder brought into the shack, come with a little misconception. One commonly repeated myth or "theory" is that halfwave antennas, being resonant, do not require a counterpoise, or that some magical length of antenna will prevent RF in the shack. This does not mean the antenna will be worthless and not make contacts, it simply means something else replaces the missing counterpoise area and we also bring RF fields right into the shack. The feedline, as well as everything connected to and surrounding the singlewire feedline and counterpoise, becomes part of the radiating system. This creates three potential problems: The feedline, mast, and things around the feedline connect through the antenna into the receiver. This brings noise into the receiver. The feedline, mast, and things around the feedline become part of the radiator. This brings voltage (electric fields) and current (magnetic fields) directly into the shack.
    [Show full text]
  • Design and Optimization of Electrically Small Antennas for High Frequency (Hf) Applications
    DESIGN AND OPTIMIZATION OF ELECTRICALLY SMALL ANTENNAS FOR HIGH FREQUENCY (HF) APPLICATIONS A DISSERTATION SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HAWAI‘I AT MĀNOA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN ELECTRICAL ENGINEERING DECEMBER 2014 By James M. Baker Dissertation Committee: Magdy F. Iskander, Chairperson Zhengqing Yun David Garmire Victor Lubecke John Madey Keywords: Compact HF, Coastal Radar, Electrically Small Antennas Copyright By James M. Baker 2014 ii ABSTRACT This dissertation presents new concepts and design approaches for the development and optimization of electrically small antennas (ESA) suitable for high frequency (HF) radio communications and coastal surface wave radar applications. For many ESA applications, the primary characteristics of interest (and limiting factors) are lowest self- resonant frequency achieved, input impedance, radiation resistance, and maximum bandwidth achieved. The trade-offs between these characteristics must be balanced when reducing antenna size in order to retain acceptable performance. The concept of “inner toploading” is introduced and utilized in traditional and new designs to reduce antenna ka and resonant frequencies without increasing physical size. Two different design approaches for implementing the new concept were pursued and results presented. The first design approach investigated toroidal and helical designs, including combinations of toroidal helical antennas, helical meandering line antennas, and additional designs incorporating toploading and folding to improve performance. The other approach investigated fractal-based designs in two and three dimensions to improve performance, reduce size, and lower resonant frequency. The performance characteristics of fractal geometries were analyzed and compared with non-fractal designs of similar height, total wire length, and ka.
    [Show full text]
  • The W1SFR End Fed 35' Random Wire Antenna with 9:1 Unun
    The W1SFR End Fed 35’ Random Wire Antenna with 9:1 UnUn What is a random wire antenna and how does it work? The term “random” infers that you can use any length of wire you want as an antenna, while that basic fact is true, there are some practical considerations. And I’m going to keep this VERY simple because there are scores of books dedicated to antenna design and efficiency. There are exceptions to just about everything I say here, so please no flaming emails from you experts out there! This ex- planation is for those whose knowledge of antenna systems is limited. The majority of modern transmitting equipment is designed to operate with a resistive load fed via coaxial cable of a particular characteristic impedance, often 50 ohms. To connect the power stage of the transmitter to this coaxial cable transmission line a matching network is required. For solid state transmitters this is typically a broadband transformer (inside the radio) which steps up the low imped- ance of the output devices to 50 ohms. To match the inpedence output of your radio, ideally, you would have an antenna system that also measures 50 ohms so that it “matches” your antenna’s input and when it does that would be called a “balanced” antenna. Usually, this comes in the form of a standard dipole built to a specific length to cover a specific spread of frequencies on a specific band. All well and good if you want to just oper- ate on one portion of one band, but what if you want to operate with the same antenna on different bands and need to have that antenna simple to deploy and highly portable? That’s where the random wire antenna really shines.
    [Show full text]
  • Technician Class License Course Chapter 4
    Technician Class License Course Chapter 4 Practical Antenna Systems Sec 4.4 26 Jan 18 K0NK The Dipole Pg 4-11 • The most basic antenna — The Dipole – Two conductive, equal length parts. – Feed line connected in the middle. • Dipoles are easy to make and easy to use Typical HF Dipole Installation Pg 4-11 Most dipoles on the lower bands are oriented horizontally and radiate a horizontally polarized signal. Broadside Radiation Pattern Pg 4-11 Dipoles radiate the strongest signal broadside to the axis of the dipole Broadside Radiation Pattern Pg 4-11 Azimuthal Pattern Computer Generated Sketch Dipole Length Pg 4-12 Total length is ½ wavelength (1/2 l ). Estimated Length (in feet) = 468 / Frequency (in MHz). • For 146 MHz: 468 / 146 = 3.2 ft = 38.5 inches • For 50 MHz: 468 / 50 = 9.33 ft = 112 inches • For 28.5 MHz: 468 / 28.5 = 16.4 ft 7 Dipole Length Typical lengths for common ham bands We shorten the antenna to raise the frequency Building a Dipole Hint: Make the element a few percent longer than needed, then check the SWR. Shorten the antenna until it is resonant at the desired frequency. SWR Measurements 4-10 The length of each leg of the antenna is adjusted to provide a low SWR on your favorite part of the band. 10 Common Dipole Configuration Fan Dipole The Ground-Plane Pg 4-12 The Ground-Plane • Is simply a dipole that is oriented perpendicular (vertical to the Earth’s surface). • One half of the dipole is replaced by the ground- plane.
    [Show full text]
  • Cat Swarm Optimization Algorithm for Antenna Array Synthesis Nirmala Yerpula A, Dr
    Turkish Journal of Computer and Mathematics Education Vol.12 No.2 (2021), 1466 -1474 Research Article Cat Swarm Optimization Algorithm For Antenna Array Synthesis Nirmala Yerpula a, Dr. A A Ansari b and Dr.M .Surendra Kumarc a Research Scholar, Dept. of Electronics and Communication Engineering, Sri Satya Sai University of Technology & Medical Sciences, Sehore, Bhopal Indore Road, Madhya Pradesh, India b Research Guide, Dept. of Electronics and Communication Engineering, Sri Satya Sai University of Technology & Medical Sciences, Sehore, Bhopal Indore Road, Madhya Pradesh, India c Research Co-Guide, KLR College of Engineering and Technology, Palvoncha Article History: Received: 11 January 2021; Accepted: 27 February 2021; Published online: 5 April 2021 Abstract: Cat swarm optimization (CSO) is a developmental technique enlivened by the animals in Mother Nature for taking care of optimization issue. Short of what multi decade after CSO is proposed, it has been improved and applied in various fields by numerous scientists as of late. CSO is created by noticing the practices of cats, and made out of two sub-models, i.e., following mode and looking for mode, which model upon the practices of cats. The prerequisite of high directivity signal with extremely quick pillar guiding is preposterous by a solitary antenna. This imperative is aid by staged array antenna which is a mix of various little antennas that can create shaft with high directivity with quick electronic pillar guiding. The radiation example of an antenna array relies firmly upon the weighting technique and the math of the array. The issues related with pillar design causing high obstruction in communication which confine them use by and by.
    [Show full text]
  • SCARS Technician / General License Course Week 4
    SCARS Technician / General License Course Week 4 Radio Wave Propagation: Getting from Point A to Point B • Radio waves propagate in many ways depending on… −Frequency of the wave −Characteristics of the environment • We will discuss three basic ways: −Line of sight −Ground wave −Sky wave Line-of-Sight • Radio energy can travel in a straight line from a transmitting antenna to a receiving antenna – called the direct path • There is some attenuation of the signal as the radio wave travels due to spreading out • This is the primary propagation mode for VHF and UHF signals. Ground Wave • At lower HF frequencies radio waves can follow the Earth’s surface as they travel. • These waves will travel beyond the range of line- of-sight. • Range of a few hundred miles on bands used by amateurs. Reflect, Refract, Diffract • Diffraction occurs when a wave encounters a sharp edge ( knife-edge propagation) or corner VHF and UHF Propagation • Range is slightly better than visual line of sight due to gradual refraction (bending), creating the radio horizon . • UHF signals penetrate buildings better than HF/VHF because of the shorter wavelength. • Buildings may block line of sight, but reflected and diffracted waves can get around obstructions. VHF and UHF Propagation • Multi-path results from reflected signals arriving at the receiver by different paths and interfering with each other. • Picket-fencing is the rapid fluttering sound of multi-path from a moving transmitter “Tropo” - Tropospheric Propagation • The troposphere is the lower levels of the atmosphere
    [Show full text]
  • Owners Manual for the Packtenna Mini
    Owners Manual For The PackTenna Mini By Nick Garner N3WG and George Zafiropoulos KJ6VU Quickstart With The 9:1 Random Wire Version You can identify this version because it has a yellow shrink wrap on the antenna body. This version of the antenna is designed for use with an antenna tuner. The 9:1 transformer will bring the antenna’s impedance down to a range that a typical tuner can handle. The antenna is supplied with about 40 feet of antenna wire. The wire should be a non-resonant length on any band you plan to operate. We recommend cutting the antenna to about 29 feet. This is a convenient length because it can be run up the entire length of our fiberglass mast and it is not a multiple of a quarter wave on any HF ham band. 9:1 coil * Requires tuner Cut to 29’ for random wire Good length for random wire: 29, 35.5, 41, 58, 71, 84 feet Cut wire to 29’ or another non-resonant length Quickstart With The End-Fed ½ Wave Version You can identify this one because it has a black shrink wrap on the antenna body. This version of the antenna MUST BE CUT TO LENGTH on the band you want to work. This antenna is a tuned half wave antenna on the desired band. The high impedance feedpoint of the end fed half wave requires a high transformation ratio of 50:1 to bring the feedpoint impedance down to 50 ohms. This antenna does not require an antenna tuner. For 20 meters a good length is about 31’ 3”.
    [Show full text]
  • NVIS Antennae Designs
    AAR2EY All Band NVIS Antennae Designs Updated 20 May 2007 Updated 23 February 2006 Updated 9 November 2005 Started 13 February 2004 As user of MF/HF frequencies, a dedicated a Near Vertical Incident Skywave (NVIS) is a requirement and not an option in my opinion. In addition a broadband NVIS antenna is a necessity for MARS/SHARES operations and especially for Automatic Link Establishment (ALE) operations. As such I offer three proven antennae designs herein for consideration as effective, inexpensive and easy to install and maintain NVIS antenna types. This piece was originally written a few years back to assist my fellow NJ Army MARS members in achieving better performing NVIS antennae installations to improve our statewide operations as many members were using anything but a proper NVIS antenna at that time. In the years since then I have been working with many Tri-Service MARS stations setting up antenna for use with ALE operations up and down the East Coast and in land which I personally communicate and the performance results of members changing over to NVIS antenna have been clearly seen. As to an ALE focus in particular, everyone needs to not only be using an optimal NVIS antennae, but also a broadband NVIS antenna due to the automatic frequency hoping nature of ALE. At present the MARS channels for our current 24/7 ALE network span from NVIS through Skywave where a 10 channel MARS Tri- Service ALE network exists from 2Mhz to nearly 28Mhz, thus random wire antenna performance with gain above 12Mhz is of interest.
    [Show full text]