All About VERTICAL ANTENNAS Theory, design, construction, operation The secrets of making verticals work Verticals and “slopers” for the best DX How to use your tower as a vertical antenna Compact verticals for restricted locations How to make an efficient “radio ground” All about loading coils and antenna tuners: Short verticals that cover 40-160 meters WILLIAM |. ORR, W6SAI STUART D. COWAN, W2LX All About _ VERTICAL ANTENNAS Cun Wer an stone tana can bs anges. Al Siuningson ir eupeent @ alepoatrgand 6 Incrciens shai be adhered, Wace svete aren woken aie sr a yor steno oot pee ‘portal Denolatarpo cers ator wiht a sey bet tisbost i worcen you anna wneomeane who can ist yo ih coe andl bo ae lohepin even pblemaran enero Cconyriah 9 188 hy Rai ans. be ibs 10 by Ras mater Cae (aninpint! VateonGupePusiatons, {cian of BP Comnuncaions, Lary Congess Canon Sad Number 86.0614 Kewesmooior Alvghisrsoned. no pan. es pnscasn may be reco ed nan fom ay eear—aok icing eistoraten sora and minocalysions—winen ‘enter sumeson ofa poset Nenuladueai ne Led Sistes ot Aneta 12945678901 01909¢97 9085 9435 cHPTER 1. cunerer CHRPTER copra as a a ‘TABLE OF CONTENTS {THE REAL-LIFE VERTICAL ANTENNA... Ho vertical antentas vork. ‘THE RALIO CROUND. ++ eeee po) How ground affects antenna operaticn. PRECTICAL WARCCNE ANTENNAS... <20+.02+2-87 Dx antennas for the “lew bands", ANTENA MATCHING DEVICES. 4++s+2200+00297 Mntehing the antenna te the tranomiteer, Popular designs for the hf-vhf bands. PHASED VERTICAL ARRAYS, easnel3 cain antennae" for BX operation Antennas for the space-Limited anateur. ANTENNA ROUNDUP... Soest Tdeas to make your antenna work betcer: FOREWORD ‘he Vertical Antenna: How Tt cane From Where Te Was ‘% Wnere Tt Te Today In 1836 a young Ttalian acientiat arrived in Luggage. The 2ustons officials, who had seen nothing Vike it) sefoco, sxanined it ce thoroughly that the Gelicate apparatus vas completely weoeked. This wae te inauspicious beginning sf 2 venture that wes Gestined 20 revolatioxize tho communication pattern bf the suentisth sontary. Guglielmo Yarconi, rowever, forged ahoad with ‘nig unuoual oeporimenso and vont dowa in history as the father of radio commuzica-ion, Ove of his greatect inventions in chis field was the antenma ‘and today a descendant of that early device is Iaown inspiration of combining an elevated wire sed in thunderotorm experinents with lis cule suurk fransnitter. The inprovenent in performance wa magical. Mexcont, by cystumlic experismnte, found his radio range was extended inmediately from yards te severe: mes, Tue adlilion o: @ celegrapn Key to his apparatus created 2 complete conmunicazion yoton wick Marconi yatented in” 1896-"yhen he was 2 yeers old. Marconi continued to improve his wireless systen and his vertical antenna hae rightfully taken its place in nistory as 4 pract:cal device for Long istance communication, ‘This new handbook concems itself with the vertical antenna in all its popular foms for hf and vhf communication. Conputer-derived antenna designs are given for amateur bands and information is provided to alloy many of the desims to be used on frequencies falling outside the amateur ascignoonts. Inpartant dimensions are qiven in both English and Metric systens. ‘The authors of this antenna handhock started experimenting with vertical antennas in 1934. Curing fium decades they have learned a good deal about these interesting and practical antennas, but there fe still muh to he discovered. There is no reascn why you cannot experiment with, and inprove on, the Entenna designs in this handbook. (Good luck and good Cx! ‘ Gone ARG, 258 four 1982 Chapter 1 The Realtife Vertical Antenna D ximple description af a vertical antenna iz ans whose active elesent 1e vertical with respect to the earthiz. surfare, and which radiates a vertically polarized wave (Fig. 1). This rerresentation shows a Talia wave travelling ont of the page tovarda, the fender. By definition, wave polarization is vertical Uren the electric field of the wave is perpondioviar to the earth, The complete radio wave consists of an interplay of energy Between the horisontal ragnctic Hield and the vertical electric field (Fig. 2). If the position of the fields ie reverced, the wave is horizontally polarized. In fro space the Getinition ic meaningiace, ao the carth'a sueface a ‘a reference does not exist. In proximity to the carthy polarization is important as the surface of the earth reflects radio Swavec. The rooults of this reflection depend upon, wave polarization, the height of the antenna atove ‘the eacth, and conductivity of the eaath. Beound Reflectiat A adie wave hugyiny Lie suctane of Lie warth ds called a sarface, 2r 3round vave, and is useful only for short=rangs conmutication, as it is eventually absorbed 2y the earth, or wanders off into space, Absorp:ion is less or longer waves than Cor shorter ‘ones, and the radio canga of ground waves in the 8 VERTICAL ANTENNAS Fig, 1 Heacton view of verialypoltlzed redo wave. The magneti tines force are paral tothe euth avd the elec lines offorceeut the sur face ct the enrth, The compete wave consists of anInerplay 0” eneray bot twoen the bo fore Held Fig, 2Ealyintarpetaton ofa vertically polarized radio wave showing elec: Ie Feld tadated trom antenna. (Wom "Wireless Telegraph and Teleprony', by Ashley and Lewis, 1911) a Pax rat Fig. 2 Reflection of radio wave from vertical antevna a2ove perec, fat, tarth. The wave roceled ata distant point conssis of a arect wave plus Wave created by ‘ellecion fom the greund, This ation compares fom {orrefection andthe laws ofopties apply equally wel to rao wave reflec: tion. Feiec'ea wave canbe consideredto come from an “image antenna ‘bested as far below the earth's surace asthe ral antennas above it {trength ofthe reflected wave depend upon antenna neigh end ths On ductivity of the earth, broaccast bind may be rundyeds of niles under good conditiors. Ground wave propagation in the hf spectrum, on tne otter hané, iz limited to tena of niles, end is primarily Linitec to the horizon in The vht spectrun. Lorg distarce HE propacation takes Hlace mainly becouse of wave xoflection from the aonosphere, ae discussed later in this clapter. Fig. 2 Sheva a vertical antenna above a perfect, flat ground. At a distant peint a wave received fron his antenna consists of a direct wave plus the wave ereated by reflection fron the ground in ‘the vicinity of the antenna. at amore distant pcint, 0 VERTICAL ANTENNAS only the reflected wave ig esccived, his action can be compared to mirror reflection and the lave of optica that govern aixrora apply equally well to radio wave <eflection, In the geteral case, the langle of the ineident ware from che anteina to the gzound (a) equals the angle of tho reflected save (), with a po: ee bag absorbed or ref-acted by the respect to anzenna heigh= above ground, the angl2 of Feflection, and also the reflective efficiency conductivity) of the groind.the vertical @eternine’ by the sum of the direst wave fron the antenna ana the gzount-rerlec:ea vave. In the case of a horizon-ally polarized antenna (a dipole, tor example), retiection trom a pertact, flat ground gives a phase (polarity) shift for the Ferlectea wave o: 18) ceqrees at mos: angles azove the torizon with little wave atzenuation, sen over poor, Joy conductivity ground, ne reflected vave retains nearly the same phase <elazionship to. the Gixect vave aad almost the ane intensity, 23 ground absorption is lov. Thus, the reflected wave patterns obtained over real-life ground closely sesenble theoretical results deternined mathematically, Ground ref-ect-on produces quite different results in the case of the vertical antenna, Theze ie 1i:tle phase shift of the reflected wave at high rerleczion angles, but a considerable phase shift a: lover reflection angles. As an example, for a very anall reflection angle |b) when the vertical antenna ie close to the ground, the phace chift of the reflected vave is nearly 180 degrees when ground absorption is snall, just 2s -n the case of the horizontal antenna. But as the reflection angle increases, the phase shift decreases until, at a critical ‘Brevster angle", phase sh:ft drops to 90 Gegrees and vave attenuation is a mazimun, thie critical angle ranges fron about 10 decrees above ‘THE REAL-LIFE VERTICAL ANTENNA n — ‘caused by ground retecton tor verteal ard olarizatons. The phase stays viruallyeonstant al 160 cegrees ioral polarization end changes subatartally fr verleal potares lion. Phase ciange tekes place at an angle of rllection between 10 ard 0 degrees dependingupen coll cnductivily (Drawing eourteny of "Motte Radio Technology" magazine) the horizon for good ground (a salt marsh,fer sxample) to over 30 dogroce for low conductivity (cocky, sandy) ground (Pig. 4), at this angle, the redistion pattern of a vertical antenna is affected the tost by ground reflection. Bolow the Deewoter angle the reflected wave fu: a vertical antenna partially cancels the direct wove waile above thie angle ground seflestion anharces the direct wave, providing a gain up to 6 Gecisels over free-space wauditiom, This yain ds theoratical, ano antenna in the vicinity of the cert) Le in Cove opens Tn any case, the better the ground conductivity, the lower Lie vrilieal angle and the greater the loy-anglo radiation fron the vertical antenna. This say be Lie ceason that suca conflicting results are reported by amateurs using vertical antennas. Those sntvurs Living in areas of poor ground conductivity are bound to have poorer lov-angle radiation from 3 2 VERTICAL ANTENNAS siver vertical antenna then those amateurs “uckr Gnowsh to yesice in a region of very good ground condtetivity, Fortunately, except for desert areas fond xogicna vith very recky coil, moct of the United States lies in ar area having fair to good ground conductivity (Pig §). Giuuid Reflection Patterns for Vertical antesnas ever horizontal, especially when antenna space is Limited. Fig. 6 compres Ure vertical cield pattern of @ horizontal dipole and a quarter-vave vertical gnterna located above good ground. ay an exanple, assume that for long distance connonication & Yertical radiation angie of 20 cegrees or less 19 cesired. ‘To actieve maxumun radiation at this ange, :t 18 recersary to place the horizonta: antensa’ abou! ‘THE REAL-LIFE VERTICAL ANTENNA 13 Fig. 6 A comparison o! the verti jleldpatterns ol horzontaland verti ilewiss located ab2ve good ground, "he horizantal antenna is 3/4 wavelength above grounc while the Ease o verti anicnnais et ground ‘Evel, 3othantennes provide yuo redatlon ata vereal angie ot about 20 degrees but horizontal antenna must be 52 feet hight do the Job onthe 3/a-vavelength above ground, The vertzeal antenna, Nertical angle when the base is ct ground level. For the 20 moter band, this requires @ lnaicoute: enterna heicht of about $2 feet (15.8m) compared with an cversl1 height of only 26.3. feet (Sm! for the vertical antenna. “ VERTICAL ANTENNAS ‘THE REAL-LIFE VERTICAL ANTENNA 6 Fg, 7 Vertes redation pattem of avert level, Over pertect ground, tow angle radiation is maximum acne 9 found (),typeal of the United Sates, some e lon floss Pex ground comltvly (©) reduces racation fall varied angles. ‘Theoretically, the vertical antenna provides a meximim radiation field dom to sero degrees (the horizon), as shown by the dashed line. However, since the wath i nut a pexfect conductor, the ‘extrene low angle radiation is not realizable, Mole Ulal Ue very ig auyle solialion lobe uf the orizontal antenna ie Useleas for most long Gistance, Ingh frequency comuieation, Tt iy eis high angle lobe, on the other hand, that makes this Fig, 8 Vorteal radiation patior cf a ground plane antonna withthe baso at grcund level resembles vertical dipole pattern, with ground absarptlon losses showing below about 15 dagrees. A= perfect ground, B= average grourd, C= poor ground. anteana type ourperforn the vertical on short-haul communication on ths lower frequency bands (160 and SO meters, tor example). Te alevation pattern of the vertical antenna at various 3eignts above grouni shows interesting low angle radiation, The pattern of a vertical dipole ‘hoss base is at ground level is shom in Fag. 7. Over perfect ground the low angle radiation is naxiaun at the horizon as shown by curve A. Over average ground (typical for the USA), sone of the 6 VERTICAL ANTENNAS ‘THE REALLIFE VERTICAL ANTENNA 7 Fig. 9 Vertical radiation pattern of aground plane antenna withthe base “lnuated onechlf wavelength shove round. adlallon le coneantrted mt ighly lower angle than when ariennals grcund mounted. Second lgh- ‘angle lobe appears at about 60 decrees above the horizon. A= perfect ‘round, B= average ground, C= poor ground. extremely low aiwjle cedielion is lost but at an elevation angle of only 15 degrees, for example, the Faalation lobe t¥ dow levy Usa 308 in pues Ceo ‘the maximum theoretical value (curve B). Poor ground conductivity, such as found in dry, sem-desert ‘areas, further reduces lov angle radiation, as shown The elevation pattern of a quarter-wave ground plane antenna with the base at gcound level 8. shown dn Fig. 8, the pattern is much the same as that of @ und plane antenna withthe kaso angle lobe crops ‘ground, C= poor radiation pattem of three-quarters wavelengin above ground. to about 40 degrees, A~ perfect ground, B= svor Vertivel talf-wave diyole, with ground absorption Joss showing at argle: below about 15 degrees. In most typical installations radiation Below” 10 degrees is virtual!y zero. ‘he Elevated Vertical anteana Fig. 9 represent the pattern of a ground plane antenné with the base elevated one-half wavelength above the ground. Radiation is coucentrated a: a