ECAC LIBRARY - DTIC
ECAC-CR-83-200 Cy. :Q DEPARTMENT OF DEFENSEElectromagnetic Compatibility Analysis CenterAnnapolis, Maryland 21402FIELD ANTENNA HANDBOOK¶Pieparad forJoint Chiefs of StaffJUNE 1984CONSULTING REPORTPrepared byJames A. KuchtiT Research histitutetinder Contract toDepartment of DefenseApproved for public release; distribution unlimited.ECAC LIBRARYYou are persoiw, IU Fc'-oat tu.e tot thisbook. O0 NO1 tianster this boua to anoL,4fibraryperson without permission ol the,, - , , '"- ' " "-; -.'---- 08 '-5v;" --' "%
ECAC-CR-83-200This report was prepared by the IXT Research Institute as part of AFProject 649E under Contract F-19628-80-C-0042 with the Electronic SystemsDiVision of the Air Force Systems Command in support of the DoDElectromagnetic Compatibility Analysis Center, Annapolis, Maryland.This report has been reviewed and cleared for open publication and/orpublic release by the appropriate Office of Information (01) in accordancewith AFR 190-17 and DoDD 5230.9. There is no objection to unlimiteddistribution of this report to the public at large, or by DTIC to the NationalTechnical Information Service (NTIS)."ý/e,ý-JAIES L. SMALLProject Manager, IITRI!eviewed byDirector of ResearchContractor OperationsApproved byCHlARLES L. FLYNN, CoIe,oSAFDDirectorSn3. C.o,USMCMarine Corps Deputy Director
WIC[Aiss!iNSECURITY CLASS'FICATION OF THIS PAGE .nDa* Ente.,.ed)REPORT DOCUMENTTIONINSTRUCTIONSREPORT DOCUMENTATIONPAGEI. -i.REPORT NUMSERBEFORE COMPLETING FORMI.RECIPIENT'S CATALOG NUMBERGOVT ACCESSION NO:ECAC-CR-83-2004. TITLE (and Subtitle)S. TYPE OF REPORT II PERIOD COVEREDFIELD ANTr-NNA XMDIOOKCONSULTINGG. PERFORMING ORG. REPORT NUMBER7.rI!S.AUTMO'(s)A. Kucb*JamiasCONTRACT OR GRANT NUNMER(*)F-19628-80-C-0042# lOPCDRLI,.PERFORkmIOAG C'.AHIZATION NAMF 'NOADDRESSDolt) E.!ctromanetJc Compatibility Analysis Center10.PROGRAM ELEMENT. PROJECT, TASKAREA 6 WORK UNIT NUMBERSNorth SevernAnnapolis,D 214U2P055312.11. CCNTROLLING OFFICE NAME AND AODRESSREPORT DATEJUNE 1984Joint Chiefs of StaffIS.NUNSER OF PAGES98A4. MONITORING AGENCY NAME IADORESS(i1 different 1,- Cont o 4inOffice)it. e1S.SECURITY CLASS. (of this tepot)DE tA IFWCA N/OOWNG tADIN G%CwEDULEDISTRIBUTION STATEMENT (of thie Report)Approved for public release; distribution unlimited.17.DIST RISUTION STATEMENT (.1 Ut.e &.ettctII.SUPPLEMENTARY NOTES13.e*.edin Block 20. Ii di U.ltent tKEY WORDS (CoAItimm an to ** aOd. Ito%***w.and 14itReport)Ay blok kMi&ANTENNASHIGH FREQUENCYPROPAGATIONVERY HIGH FREQUNCY10ASSTRACT (C tinua.tNaide If A4ceseeldttqrby StackThis handbook presents basic propagation theory, the fundamentalsconcerning antennas, and the design and use of tactical hiqh frequency andvery high fvtquency antennas.It is a field reference for basic antenna facts*and a usage guide for antennas.DDJAO t14139OiTIOM OFINOV&S ISOBSOLETESECURITY CLASIIFICATION Of ThIS PAGE (Ifto. .-.DOataEatek'd) .
,.-,.-, i. ".y-.r:.--. -TABLE OF CONTENTSTitlePageINTRODUCTION . . . . .SECTTJN IHF AND VHF PROPAGATION FUNDAMENTALSHIGH FREQUENCY COMMUNICATIONS"Ground-Wave(2 TO 30 MHz).3Propagation34Sky-Wave Propagation .VERY HIGH FREQUENCY COMMUNICATIONS (30 TO 88 MHz) .8SECTION IIANTENNA FUNDAMENTALS*WAVELENGTH AND FREQUENCY ."RESONANCE12.POLARIZATION.*.**.9******.*.* REFLECTIONS .,1313-GAIN15STAKE-OFF ANGLE .ij'11s*.PATTERNS . . so.1516SECTION IIIHF ANTENNAS*i*GENERAL .*- DETERMINING ANTENNA GAIN .24"ANTENNA SELECTION PROCEDURE .2.21Selection Procedures .25"Example .25,AS-2259/AS-2263 .27
TABLE OF CONTENTS (Continued)SECTION III (Continued)TitlePageOE-85/OE-86 .*VERTICAL WHIP .DIPOLE. . .S HALF-wAVE,**.29.3135. .INVERTED VEE.41LONG WIRE .43.6A.INVERTEDSL2.,. .764.4952SLOPING VEE .WIRE .i3SLOPINGVERTICAL HALFRHOMBIC5. .7.SECTION IVEDVHF ANTENNASRKALA. . .O.NGEPAIERRC-292OE-254 .AS-2236 .6.*. . .6966.870AS-285.1 .72VERTICAL HALF RLHOMBICiOE-303 .75SECTION VEXPEDIENT TECHNIQUESREPAIR OF BROKEN ANTENNAS .INSULATORS .SUPPORTS .-. .4.TERMNATIG RE IST RS .79.t oo. .iv.8080. .8
.4uTABLE OF CONTENTS (Continued)SECTION V (Continued)-.TitlePageE .XPEDI ENT WIRE .,.GROUNDING .82. . .SECTION VI"FOR MORE INFORMATION85.V/vi
a,'INTRODUCTION* "Of all the variables affecting communications,the onefactor that the individual o-erator has the most control over isthe antenna and its use.By using the proper antenna, anop -ator may change a marginal circuit into a reliable circuit.This handbook presents basic propagation theory, the fundamentalsof antennas, and the design and use of tactical high frequencyand very high frequency antennas.A working knowledge of this"handbook will allow the operator to properly select and employindividual antennas to provide the strongest possible signal atthe receiving station of his circuit.This handbook is notintended to be a technical handbook on antennas, but is intendedto be a field reference for basic antenna facts and a usage guidefor antennas.Sections I and IIpresent information which should beunuerstood by radio operators, however, this handbook can be usedwithout thorough knowledge of those sections.Section IIAcontains HF antenna selection procedures and describes the morecommon tactical HF antennas.Section IV does the same for VHFantennas.Section V presents info rmation on making antennasusing field available materials.Section VI lists publicationsavailablefromthedifferentservicesthat give detailedinformation on piopagation and antennas.1/2
SECTION IHF AND VHF PROPAGATION FUNDAMENTALSPropagation is the process by which a radio signal travelsthrough the atmosphere from one antenna to another. This sectionbriefly describes the propagation factors that need to be knownto better understand the antenna information presented in thefollowingsections.Thissectionisdividedintotwo majorparts, high frequency (HF) propagation and very high frequency(VHF) propagation.Each part can stand alone so that the radiooperatorinterestedinonly HF orVHFcommunicationscangodirectly to that part.HIGH FREQUENCY COMMUNICATIONS(2 TO 30 MHz)High frequency communications is accomplished by eitherground-wave or sky-wave propagation.With current low-poweredman-pack radios, ground-wave communications can be establishedout to 20 to 30 kilometers (kin).High powered equipment (mountedinjeeps and vans)can extend that range to approximately 80 to100 km. The coverage from sky-wave communications, on the otherhand,can varyfromseveral kilometersto thousands ofkilometers.Ground-Wave PropagationGround-wave propagation involves the transmission of a radiosignal along or near the surface of the earth.The ground-wavesignal isdivided into three parts:the direct wave,thereflected wave, and the surface wave.The direct wave travels through the atmosphere from oneantenna to the other in what is called the line-of-sight (LOS)mode.Maximum LOS distance is dependent on the height of anantenna above the ground; the higher the antenna the further themaximum LOS distance.Because the radio signal travels in air,any obsttuctions, such as a mountain, between the two antennascan block or reduce the signal and prevent communications.Foran antenna 10 feet above the earth, a maximum LOS distance ofabout 6.5 to 8 km (4 to 5 miles) can be expected.The reflected wave, like the direct wave, travels throughthe atmosphere but reflects off the earth in going from thetransmitting antenna to the receiving antenna.Together, thereflected wave and the direct wave are called the space wave.3
St PACESTR iMUMMATEDI CECT"SURFACEWAVERCIEWAVEWAVE ALONG SURFACEComponents of ground wave."The third part of a ground wave is the surface wave.Thispart travels along the surface of the earth and is the usualmeans of ground-wave communication.The surface wave is verydependent on the type of surface between the two antennas.Witha good conducting surface, such as sea water, long ground-wavedistances are possible.If there is a poor surface between the"antennas, such as sand or frozen ground, the distance expectedfor the surface wave is small.The surface wave range can alsobe reduced by heavy vegetation or mountainous terrain.Sky-Wave PropagationBeyond the range covered bycommunications are possible throughwave propagation is possible because"signal by a region of the atmosphereSThisthe ground-wave signal, HFsky-wave propagation.Skyof the bending of the radiocalled the ionosphere.The ionosphere is an electrically charged (ionized) regionof the atmosphere that extends from about 60 km (37 miles) to1000 k- (620 miles) above the earth's surface.The ionizationresults from energy from the sun and causes radio signals toreturn to earth.Although the ionosphere exists up to 1000 km,the area important for HF communications io below about 500 km.area is divided up into four regions:D, E, F1, and F2.The D region is closest to earth and only exists during thedaylight hours.It does not have the capability to bend a radiosignal back to earth but it does play an important role in HFcommunications.The D region absorbs energy from t',e radiosignal passing through itthereby reducing the strength of.received signals.4
The E region, the next higher region, is present 24 hours aday, although during night hou's it is much weaker thaii duringthe doy. The E region is the rfirst region with enough charge tobend radio signals.At times, parts of the E region munications. These highly charged areas are called Sporadic Eand occur most often during the summer.Structurof60 thKMoahieorH22ouuialn aeteTheWost ipCrtn reinomnctosdpnkwfHF2re ions. Temjrt nd Thebendingcofrardofsgalbthe ionosphphdepndoThhfeqenc irrtheofsradionsinlthe f wHic thwe cadommniaional dependonthenshe equencyohfwil.radibeignac, ttheisegreed the crnizticalifrequency. Each region of the ioraepher. (E. Fl, F211 will have aseparate critical frequency. Foz a vertical angle, signals abovethe highest critical frequency will pass thr.-ugh all ionosphericrogions and on into outer space. Frequencies below the critical.frequency of a region will be bent. back to the earth by thatregion; however, if the frequency is too low, the signal will beabsorbed by the D region.In order to have HF sky-wave5
communications,T,**a radio signal must be a high enough frequency topass through the D region but not too high a frequency so that itdoes not pass through the reflecting region.The angle at which a radio signal strikes the ionosphereplays an important part in sky-wave communications.As mentionedabove,any frequency above the critical frequency will passthrough the reflecting region.If the radio signal having afrequency above the critical frequency was launched at an angle,instead of straight up, the signal could be bent back to earthinstead of passing through the region.This can be compared toskipping stones across a pond,If the stone was thrown straightdown at the water it would penetrate the surface.But if theangle at which the stone is thrown is lowered, an angle will bereached where, instead of going into the water, the stone willskip across the pond.For every circuit there is an optimumangle abnve the horizon, called take-off angle, that will producethe strongest signal at the receiving station.This optimumtake-off angle is used to select the appropriate antenna for aspecific circuit.Although a radio signal is actually bent by the ionosphere,the term reflection is commonly used to describe the turning backof a radio signal by the ionosphere.Reflection will be used inthis handbook, even though bending is what actually occurs.* Because many antenna3 rmdiate energy at several angles, morethan one wave from the trananitter may reach the receiver.Anexample is shown in the illustration.Multiple transmission paths.6
Two important things are shown in this illustration.First,radio signals arrive at the receiver after being reflected fromdifferent ionospheric regions; and second, the path may consistof one or more reflections (hops) from the ionosphere.Any paththat consists of two hops or more also involves a reflection atthe ground somewhere between the stations.Path 1 is at an angle such that the wave is partially bentby both the E and the F1 regions but is reflected by the F2region.It is reflected by the earth and again by the F2 regionbefore reaching the receiver.This path is referred to as a twohop F (2F) path.Path 2, at a smaller angle, is bent by the E region, thenreflected by the F1 region.It is thus a one-hop F (OF) path.Path3isat ananglesmall enoughfor E regionreflection.It is reflected from the ground and again by the Eregion before reaching the receiver and thus is called a two-hopE (2E) path.Path 4 is reflected by the E region only once.one-hop E (IE) path.hence itis aDepending on the type of antennas used, signals can bereceived from any or all of the different paths.Because eachpaticovers a different distance,the signals arrive at thereceiver at different times.When two or more signals arrive atthe receiver from different .aths, they can interfere with eachother and cause what is called multipath interference.This typeof interference will produce echoes or motor boating on circuitseven though a receiver's S-meter shows a strong received signal.Depending on the frequency, antennas, and other factors, anarea may exist between the longest ground-wave range and shortestsky-wave range where no signal exists.This is called the skipzone.HF propagation involves much nore than what has beenpresented here.For example, multiple frequencies are usuallyneeded to maintain sky-wave communications.As a minimun, twofrequencies, one for daytime aid one for nighttime are normallyrequired.N[uerous books and field manuals exist for those whowant to learn more.The references section of this handbook7
z z zW -1K7S'U4 -.--VZ:'ý'Yd oneIliFlOSt.ac pofagatin.HF skipgaioinfluenced by four separate components that result in thethe direct ray, the reflected ray, thereceived signal:refracted ray, and the diffracted ray.*The direct rý-y travels the straight line distance from theBecause of thetrxknsmitting antenna to the receiving antenna.curvature of the earth, the maximum distance between two antennasfor a d-i ect ray is determined by the height of the antennasThe higher the antannas, the longer the&bove ta e NG,7DIRECTANTENNAWAVERTr1ansmission of direct and reflected waves.*8
.4-The reflected ray, like the direct ray, travels through theatmosphere but reflects off the earth's surface in going from oneantenna to the other.The reflected ray may cause a troublesometype of interference.The path traveled by the reflected ray is"longer than that of the direct ray, therefore the reflected rayarrives at the receiving antenna after the direct ray.If thetwo rays are "in phaset t , they will reinforce each other producing"a stronger signal.If they arrive "out of phase", one signalwill cancel the other resultii in very pocr or nonexistentcommunications.It is this cancelling effect that explains why,"at times, no signal is received even though the transmittingantenna is in sight.Moving the antennas either closer orfurther from each other, or changing the height of one oZ theantennas ahould result in a usable signal."REFRACTED RAY,.-"ANTTRANISMITTINGENNARECEIVINGANTE NNA"VHF refraction.The refracted ray is what allows the line-of-sight distance"for a radio signal to be greater than visual line of sight. The"differences in the lower atmosphere cause the transmitted signalto bend slightly back to earth.This bending permits therefracted ray to travel further than the direct ray.The VHF-LOSdistance resulting from the refracted ray is shown in thegraph.This graph indicates the distance that VHF-TLOS exists fora transmitting antenna on the ground and a receiving antenna at"the height irdicated.The height of the receiving antenna goesup to 1000 feet to allow the determination of VHF-LOS distance toan aircraft.The diffracted ray scatters around obstacles and permitscommunicationsin the shadow region behind obstacles.Lowfrequencies scatter (diffract) more than higher frequencies, soitis not ancommon for a lower-frequency signal to diffractacross a hill top and result in reliable communications at areceiver antenna located not far belom.Y the line of sight, while"at the same time a signal of higher frequeucy will not be heard.9.*o
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'T-. --1* -:-,--------'SECTION IIANTENNA FUNDAMENTALSTo1 be able to properly select antennas for a r-Ai: circuit,certain antenna concepts need to be understood.This sectiondefines several basic terms and relationships which will help thefield radio operator select the best antenna for his circuit.*.WAVELENGTH AND FREQUENCYIn radio frequency communications,there is a definite"relationship between ant-nna length anad transmitter frequencywavelength.This rclationship is important when constructingantennas for i specific frequency or frequency range.Thewavelength of a radio signal iL the distance traveled in the timeit takes to complete one Zycle.¾4-I CYCLEWAVELENGTH.,/774"0PEK\ "TIMEDISTANCEORRadio wave terms.Wavelengthis usually repreteatedby the Greek letter,A,pronounced lambda.All radio signals travel at the speed oflight.The wavelength of a frequcncy is equal to the speed oflight divided by the frequency.To find the wavelength of 3 MHz:- ""Waveengt( )300Wavelength (),000 ,ý000-M/s3.000.000 Hz- i001.0000,000meters or 328 feetThis means that in the time it takes to complete one cycle at 3MHz, the signal travels 10) meters or 328 feet.This is thedistance the signal will travel through air; the distance in awire is slightly less and will be discussed in a later section.,. '. .".',. . ".'.'." ."''.'.,'.'.'#'.j*."V.- , *-,,,. .'4" .',r ,.-",.,'.
RESONANCEAntennas can be classified as either resonant or nonIn a resonant antenna,resonant depending on their design.antenna is radiated.tothefedsignalalmost all of the radioIf the antenna is fed with a frequency other than the one forwhich it is resonant, much of the fed signal will be lost andA resonant antenna will effectivelywill not be radiated.radiate a radio signal for frequencies close to its designfrequency, usually only 2% above or below the design frequency.In practice this means that if a resonant antenna is used for aradio circuit, a separate antenna must be built for eachA non-resonantfrequency to be used on the radio circuit.antenna, on the other hand, will effectively radiate a broadBoth r
Ground-Wave Propagation Ground-wave propagation involves the transmission of a radio signal along or near the surface of the earth. The ground-wave signal is divided into three parts: the direct wave, the reflected wave, and the surface wave. The direct wave travels through the atmosphere from one
The ASM Handbook should be regarded as a set of actions implemented by the ECAC States to be used in conjunction with the EUROCONTROL Specification for the application of the Flexible Use of Airspace (FUA). The ASM Handbook should neither be considered as a substitute for official national regulations in individual ECAC States nor for the ASM Part of the ICAO European Region Air Navigation .
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