A, V ROE CANADA L!Mll E O TECHNICAL DE.PARTMENT (Aircraft) FH: PcRrNc 71/SYSTEN P. 13/3 'IC> CF SH EEt'9' ~14.:.<.·------- T!Tt.E ANTENN/\ EVALUATION PROGRAM, CF- 105 PR£-PA.PEO BY H. L. Pollock n .t,Tf" July /57 ~HECKED B'( K. J. Keeping DATE July /57 suP"""''sEo er 'II. Taylor nm• Sul:r 157 A-P,PF>GYED 8'( DATE l I . 1 • ee:POR1' -N _. .,, TA.~LE OF ILLUSTRATIONS Fig. ( l) RefJ.ec ti On From A Spheric,al Sur.face F'ig. (2) Reflection Properties Of fresh Water Fig. (3) Ground Sta ti on Antenna Gain At 226 . 8 Mc/s Fig. ( 4 ) GJ"ound Station Antenna Gain At 277. 0 '/leis Pig. ( 5) Gr otmd Station Antenna Guin At 324, 3 L!c/s F'lg. ( 6) Ground Station Antenna Ga:!.n "t 384 , 3 f!c/s !"i~ . ( ?) Ground Sta t ion ~ecorrle~ :ndication Fig. (8) Ground Station S1stec Ng. (9) AirhOl'ne Syste~. HLP/jroy I Ju11151 O MA L TO N · ON T ~RI O SHE ET No TECHNICAL DEPARTMENT PREF'ARE D B Y C A TE A,~TE~NA EVALUATION H. T.. Pnllo"lr .Tulv/C:,7 CF-105 PR OG RAM, CF-105 C HECK E D B Y GENERAL Cont'd ••••• It will be a requirement for this program that all flight test data be repeatable to within 1 db. In flight pattern measurements will be repeated at least once, and on a different day, in order to ensure that atmospheric cond i tions and faulty equipment do not influence the data obtained. Data will be obtained for several frequencies within each of the UHF and L-Band spectra. Calibration of the ground station antennas will be per formed for each flight immediately before commencing pattern measurements. This will ensure that the eff ect of ground station lobe structure does not influence the resu lts. It is proposed to choose a fli 6ht path such t hat the Fresnel zones of interference lie in a body of water, thereby ensuring a constant ground conductivity in the significant portion of the region surrounding the ground station antenna installation. Since fresh water, rather t han sea water, is immediate ly availabl~ in the Toronto area, the ground station will be designed using it as a reflecting media. 3. GROUND STATION EQUIPMENT 3.1 Antenna Installation In order t o ensure that the ground station an tennas provide the necessary coverage to the aircraft when it is over t he test location, it is necessary to adjust the height of the iso tropic UHF antenna f or each frequency to be test ed in that band. Only one L-Band antenna height is required since this antenna is directional and will not be affected by multipath transmiss ion. It is proposed to -evaluate the UHF System at any three of the four frequencies, 226.8 Mc/s, 277.0 Mc/s, 324.3 Mc/s and 384.3 Mc/s; and the L-Band system at 970 Mc/s and 1060 Mc/s. DATE )Mg REPORT N O. ys ems A~RO A IR C R AFT LIM/TEO 'l M AL.TON , ON T ARI O SHEET NO Z1/S t 1313 TECHNICAL DEPARTMENT PREPARED BY DATE AIRCRAF"T: CF-105 Ai~TENNA EVALUATION PROGRAM, CF-105 CHECKED B Y 0 ATE 3.1 Antenna Installation Cont'd ••• The procedure for determining the correct ground station heights for the UHF isotropic antenna is detailed in Appendix I. Table I gives the value of g (Q), the earth gain factor for surf ace distances between aircraft and ground station ranging from 15-35 miles. Iable I - Ground Sta~ion Aa~•nna G§in f • 226.8 Mc/s f • 277.0 Mc/s Station Height 39.214' Station Height 32.120 I d g (Q) d g (Q) (miles (miles) 15.1!51 o. 7760 15.12i 0.7819 17.678 l. lli3 17.64 1.1070 20. 206 1.38 2 20.168 1.3887 22.729 1. 5366 22.692 1. 5261 25.266 1. 5900 25.217 1. 5901 27.798 1.6061 27.743 1.6100 30.~il 1. 5778 30.271 1. 5793 32. 7 1. 5263 32.aoo 1. 5081 35.405 1.4640 35. 331 1.4644 f • 324. 3 Mc/s f • 384. 3 Mc/s Station Height 27.408 1 Station Height 23.096 1 d g (Q) d g (Q) (miles) (miles) 15.105 o .. 7807 15.089 o. 7704 17.624 1.1154 17.605 1.1070 20.144 1. 3835 20.121 1. 3870 22.664 1. 5254 22.638 1. 5264 25.185 1. 5903 25.156 1. 5904 27. 707 1.6097 27. 765 1.0110 30.231 1. 5792 30.195 1. 58o2 32.7~6 1. 5275 32.716 1.5283 35.2 3 1.4669 35.328 1.4657 t See lppendix I AIRCRAFT: MK AVRO AIR C R AFT L / M ITEf) R EPO RT N o _7_1_/_S_Y_S_T_EMS __ l~3~/~3 __ MA LTON - O N T AR IO SH EET No _4 _______ __ _ TECHNICAL DEPARTMENT P REPARED B Y DATE H.L. Pol l ock Julv/fi7 CF-105 A~'t' ENN A EVALUATION PROGRAM, CF-10 5 CM E CK E D S Y 3.1 Antenna Installation Cont'd. · ••• The reflection coefficients for fresh water are given in the graph of figure (2), It should be noted that the reflection coefficients in this case are independent of frequency over the UHF L-band regions. Figures (3), (4), (5) and (6) give the ground station gain for the test frequencies over the range 15-35 miles. It is clear that maximum gain is obtained over the range 25.5 to 29 miles in all cases, Test flights should be conducted at a distance along the ground of 27.5 to 28.0 statute miles for best results. 3.2 UHF Field Strength Measurement UHF field strength will be measured using the re ceiver section of Radio Set AN/GRT-3. In this equipment, a jack is provided to permit the meas urement of AVC voltage. The equipment is so de signed that the AVC voltage output is directly proportional to the logarithm of the R.F. volt age input, AVC voltage is thus a measure of rel ative field intensity, 3,3 L-band Field Strength Measurement It is proposed to operate an APX-6, installed in the aircraft as an L-band pulsed transmitter, An APX-6, modified as stated below, will be used at the ground station as the L-band receiver. An output from the last I. F. stage will be fed t.o a slide-back voltmeter (a slide-back voltmeter indicates peak voltage) which has previously been calibrated for the pulse repetition frequency and width of the transmitted signal. The voltmeter reading will then be proportional to field inten sity, Measurements Corporation Model 67, Slide-back Voltmeter will adequately fulfill the require ments for this program. 3,4 Recording And Calibration The UHF and L-band field strength measurements will be recorded on chart type recorders and system operat~bn will be monitored continuously throughout the flight. DATE 'fts: ,u ~o ~;nrn~rr tnurro REPORT"'" 71/Sy.ate:ms l ~/3 .. A.__ • ,u-...,, 0"'TA'l 0 TECHNICAl DEPARTMENT OAT£ CF-105 A~tTEl'fNA EVAWATIOU rL L. Pollock July/57 I P'ROGRA14, .CF-10 5 1---- c-.. -~ _c_i<_£_o_a_~ - - --"'-.,-... -,-£- ! ).4 Reco~d1hg And Calibration Cont'd •••• Tbe check-point, the aircraft is approaching at an attitude different from straight and level flight, the recorder will indicate a wavy field st.r ·e.ngth pattern due to shielding effects ot the air,cra.ft as the pilot attelllpts to properly orient it. On the other hand, if the aircraft is app roaching the check-point at a straight and level attitude, the recorder will indicate a constant field strength pattern and the measurement .at tb.e check-point is then valid. Figure (7) illustrates a typical recorder pattern tor the above situations. Ground station equip ment ~ill be calibrated ror relative .field ~nten sity by simulating antenna ~ignals with approp riate signal generators before and after each flight. For each !light , prior to co1n111encing •Val11at1on ~ests. the airc r aft will riy radially tro• th• ground station passing over and beyond the check point, transmitting continuously on UHF. Trans m1s.s1on will also be made for several, other head ingis in the region of the check-point. Field stx.ength readings ror the above will be recorded. I! the maximUlll lobe of the ~F antenna does n0t occlµ' at the check-pq1n.t and surrounding reg;i.~rn, the antenna height will be adjusted and tnis pro cedure repeated until the !auit is corrected. It should be noted that the ground station is so designed that the antenna lobe maximum is suff iciently broad as to 111n1m1ze errors in fialA strength measurement whi.ch are caused by inacc uracies in locating the ground check-point. A system diagram tor the ground station is g1~en in tigure ( 8) 3.5 Conuaun1cation The transmitter section ot AN/GRT- 3 and the Stoddart UHF receiver will be used for normal co11D1un1cat1on ~1th the aircraft. I n addition, it is suggested that a te'1.ephone line hook-up be estaolished w1th the Avro plant. A. separate UHF abtenna will be required !or comm unication purposes . i} !.. _ .. ___ _ ________ _ AIRCRAFT: EK ,4v·no AIRCR ,4FT LIMITF.O MA. LTON - Of'/lAR10 TECHNICAL DEPARTMENT REPORT No 71/Sy:stems 13/3 SHEET No 6 DATE CF-105 I PREPARED SY . ANTENNA EV ALU AT ION f-'H ...... L.Ar....._..a.P.:.<01.....,.,_ 11_,,_,,., <"><'lr.,,__ ___ J-=IU,_,.,l~ v/.L.J_S,__ 7_ ! p ooGRAM, CF-105 cH E cKED s v DATE 4. AIRBORNE EQUIPMENT 4.1 UHF Transmission UHF transmission will be accomplished using the AN/ARC-34 or equivalent. This equipment is pres ently installed for normal UHF communication pur poses. As the aircraft approaches the region of of the chec~point, the pilot will depress the press-to-talk button and ground station measure men16 will be recorded. A suitable monitor will be installed in the air craft and the pilot will be required to check and record the output power at various times through out the flight. 4.2 L-Band Transmission L-Band transmission will be accomplished using the AN/APX-6, modified as follows. The modulator delay line should be replaced by a line having twice the delay of the present component. This will enable transmission of one pulse, two microseconds width, rather than the present trans mission of one pulse, one microsecond width. It is necessary to transmit at a pulse repetition frequency of the order of several thousand pulses per second in order to present a usable signal level at the ground station. This may be acc omplished by connecting a suitable pulse gener ator to the "BM TRIGGER" input of the AN/APX-6. A push button control should be provided tor activation of the pulse generator. At the app ropriate time, the pilot would then depress the button and L-Band transmission would commence. As in the case of UHF transmission, a suitable power monitor will be installed in the aircraft and the pilot will be required to check and re cord the output power at various times throughout the !light. A block diagram ot the airborne system is given in figure ( 9). AIRCRAFT· EK Al,,. RO A I R C RA FT L I MITEIJ REPORT No 71/Systems 1 ~/~ 7 M"'L T O N - ONTAR I O SHEET No TECHNICAL DEPARTMENT CF-105 ANTENNA EVALUATION PROGRAM, CF-105 PREPARED BY H. L. Pollock CHECKED BY DATE July/57 DATE 4.3 Communication Since aircraft installation space i~ at a prem ium, normal communications and UHF field strength measurement will be accomplished using the same equipment. _The pilot will transmit signals for measurement purposes only for short periods of time when approaching the region of the ground check- point' during which time it will not be possible for him to receive other communications. It is felt that this will not endanger the mission, since time of transmission is relatively short. 5. EVALUATION PROCEDURE 5.1 Flight Plan Prior to commencing field strength measurements for each flight, the aircraft will fly radially from the ground station, passing over and beyond the check- point, transmitting continuously on UHF. Straight and level flights for several other headings passing over the check- point will also be required. Calibration of the ground station will be accomplished as previously indicated. When the ground station has been satisfactorily adjusted, field strength measurements will be made for straight and level flight over the check point at twelve headings spaced 300 apart. It is proposed to measure both UHF and L-Band field strengths concurrently, however, if interference problems should arise·,. UHF and L-Band measurements will be measured consecutively. Three UHF frequencies and two L-Band frequencies will be tested. A certain amount of pilot training will be requir ed in order to properly orient the aircraft in a straight and level flight over the check point. The flight procedure is similar to Radio Compass procedures. Each pattern will be checked at least once and on a different day, in order to establish repeat ability. "iii«' AVRO AIR C R AFT LIM/TEO MAL TON ONTAR IO REPO RT No. _ _,7c...l .... l,_,S..,y~s _..t_...e_m~s~l .... 3.u/'-.3,,__ 8 SHEET NO TECHNICAL DEPARTMENT PREPARED BY DATE AIRC RAFT; CF-105 ANTENNA EV Alli AT ION f-'H...., • ._..I..._.,.'-...LP_..01_.. l .... ln.......," lc.___ __ -+'.T.._....ul...,. v~l_,_,_'57_ HLP/jmy PROGRAM, CF-105 r-----c _H_E_c_K_E_o_e_v __ --t _ _ o_A_T_E __ 5.2 Repeatability For each frequency tested, patterns taken on diff erent days must agree within 1 db in order for repeatability to be satisfactorily established. When tpis has been done, these patterns will be checked against model range data for the same plane. If there is agreement between in-flight and model range data to within 1 db, the model range data will be accepted as tpe final pattern for the antenna in question, If model data is not in agreement with flight data, it will be necessary to repeat model range measurements in order to establish the necessary correlation, Development Of Measurement Techniques The major advantage in using the above method for antenna evaluation, is that the flight time re quirements for the CF-105 are minimized. It would appear most desirable, therefore, to per fect measurement techniques well in advance of scheduled tests for the CF-105. In order to develop the necessary pilot and ground crew skills required for successful performance of this pro gram, it is suggested that preliminary UHF pattern measurements be made, using a CF-100 aircraft as a test vehicle, 5.4 Aircraft Program A summary of the aircraft program is given in Table II. It shou]d be noted that prior to comm encing pattern measurements, the ground station must be calibrated as previously described in paragraph 5.1. Calibration may be performed using some other aircraft, such as the CF-100, prior to each CF-107 flight. The data contained in Table II has been prepared under the following assumptions, (a) Field strength measurements for twelve headings can be accomplished in one hour of flight time, ground station calibration being performed by a separate aircraft prior to a measurement flight . AIRCRAFi: EK ,4VRO A / RCRAFT l /M/TE O M ALT ON . Q N T"-R IO REPORT N O. --'7_1~/_S~y~s_t_e_m_s_l~3~/_3 __ SHEET NO 9 TECHNICAL DEPARTMENT F'REPAREC BY DATE H. L. Pollock July/57 CF-10 5 ANT.ENNA EV ALU AT ION PROGRAM, CF-105 CHECKED BY CATE 5.4 Aircraft Progran Cont'd ••.•. (b) UHF and L-Band field strength measurements can be made coincidentally. If interf~ ence problems arise, separate measurements will be made for UHF and L-Band and add itional flight time will be required. (c) P•ttern repeatability may be satisfactorily established in each case by one check flight. (d) Preliminary UHF measurements using a CF-100 aircraft as a test vehicle are required in order to develop the necessary pilot and ground crew skills. Table II does not pro- vide for these. It is estimated that ~5 to 10 hours of CF-100 flight time will be re~uir- ed in support of this program. From Table II, it is estimated that total CF-105 flight time required in support of this program is 15 hours. this includes a 25% safety factor which would account for equipment breakdown, aircraft malfunction, etc. 5.5. Model Range Program A summary of the model range program associated with this project is given in Table III. The data contained in this table has bee~ prepared under the following assumptions ~ (a) Patterns shall be measured on 1/18 scale models for both L-Band and UHF frequency bands. (b) UHF measurements shall be performed for three specified frequencies, on each of two an tennas. (c) L-Band measurement shall be performed for two specified frequencies, on each of two antennas. :HIJM 1')10A Table II - Aircraft Program For CF-102 I Test (Mc/sl Freauency Of Fin Cap Area Belly Area , Estimated UHF-L-Band UHF-L-Band Flight Time ~UHF Sec- (L-Band Fliirht No. (Hours) ion) Section) UHF L-Band 1 1 226.8 970 2 1 324.) 1060 3 1 384.3 4 1 226.8 970 5 l 324.3 1060 6 1 384.3 7 l 970 226.8 8 1 1060 324.3 9 l 384.) 10 l 970 226.8 11 l 1060 324.3 12 1 384.3 Estimated Flight Time 12 Hours 25% Safety Factor _3_!lours Total Flight Time 15 Hours 0 "'ii I ...... 0 \.1\ > ~1 Qt>;! ~§ ~,. w tz.I < O;r> ';18 I-'> o~ V\H 0 :z: P:l 1--t n I ~ 5' ~~ o~ m -< ~ oi-< > \<; ~~ ~~ :::c ~ ... C"). ' ,. >'I> r- ':t::. 0 z ... c:1 ' ,., 0 ~ .,, z 'I> ,. ... ,_ =a~ '>\ -4 - .., 31: 0 ,., " z ~ -4 ' ~ "' .. I :0 "' "' "' -t .. z > 0 :0 :0 "' ~ :0 -t z 0 "' I-' " 0 o ... m ~ -< i ~ o · L > ~ -t L "' A!RCR ... F T )ixjg' A>'lf() ~tNCNllF'T l/Mll'.£:0 11EPo~T No. 71/$,Ys tems 13/3 $4££T NO ___,,l._.1..__ ______ _ M ~\.T"QN 0N 7 -'~1b UCHNICAL DEPARTMENT CF- 105 ANTE~WA &VAtUATlON P9.0G'!1AJ.f, CF•l05 PRE9 A R.EO B Y Hock ~. 5' Model Bli.nge l?rog-ram Con tc 1 d •..• (d) The allowable tolerance on models used for pattern measuTement shall be that which perm1 ts the- system accuracy for the range (t 1 db 1n 25 d'b) to be reali:r..ad. (e) SchedQles are based on a forty hour week and contain drop-out allowances. (f) Pattern me·asurements required 1n support Qf preliminary flight tests with a. CF-100, are not 11'1.clu(led in Table Ilir. It is es timated t 'h_at '172 man hours are 'l"eqtttred for CF-lGO model measul'ements and range ut11- i.zat1on would be 30 days. Table III - Model Range Program For CF-105 - !Frequency Antenna Range Util1x - Labour ( Mc/s) Model &tion ( days) (Man-houxs ) 226.8 UHF Belly 324.3 384,3 226.8 UHl". Fin- 324.3 c.ap 384, 3 120 1032 970 L-Band 1060 'BeHy 970 L-1~and 1060 ' Fin-cap 120 860 L. .CONCLUSIONS '!'he advantages of employ1n-g the above method .for the antenna eva'.luation pr·ogr;am al'e listed below~ (1) ReqQirements for CF-105 fli ght time are mioimiz. ed. Previous proposals required that flight tests for complete 360° co\·~rage be performed for each ahtenna. This proposal reqUires that !or each antenna, coverage for only a single M< ••li t flfl/J'(JI"'' ' "'Ftl>-D ..... •o ., ..... . .. TECHNICAL DEPARTMENT !--~~~~~.....::...:....:..:.;...;..;."'"'-'-' CF- 105 A'::'~'MA E'-lAWAT:!:ON I c .. .: c itEo • • i...rc P~"'G~AM, CF- 105 6 . COtiCLUS IONS Cont'd • • • .• (1) Cont'd . plane be measured by flight test, the entire an tenna pattern then being deter mined by model range techniques . (2) Aircraft and ground system instrU1:1entation re quirements are considerably reduced by virtue of the relatively few in- flight measurements required for tbis program. An automatic data reduction system, as recoa.mended for previous antenna evaluation programs, •i ll not be r equi r ed. (3) A substantial reduction in the overall cost of the program will be effective by virtue o!' the reduction in flight time requi r~Ments and co~ pl exity of 1nstrU!.'lentat1on. Previous repor ts • , indicated that approximate ly 10 hours cf CF- !.05 !'light t1:::ie would be su..'fic ient to ceasure the complete 3~0° antenna cov erage pattern for that aircraft. !n a recent trip to the U. S. Navy Air Test Centre, Patuxent, it was noted that the Antenna Group required some 50 hours of flight time to measure the com plete coverage 0f one antenna. lt would therefore appear that previous estimates were in error. (4) If, as now seems l ikely, the I rdome is to be i n stalled in the fio - cap area , the mcdel patterns and :light t es ts f or the UHF-L-o&nd fin antenna, would be deferred until an assessment of the eff ect of the !rdooe on this antenna could be made. I! the results of the IrJo~e investigation so in dica t e , it may be necessary t o relocate the :in cap antenna installation. When the e~fects of the Irdome nave been investi6ated and suitably ain1miz ed , the !JH?-L- band antenna will then be evaluated as described i n t his r eport . 7 . ' 10l:!K SCHEQULE • Tne following author! zations would be required, foll owing approval of this proposal. Uemo 2l58/02C/J, August 31 1 1956 ' .&. t!iCR,A~T. AN"!E~iiA EVALUkTlON PROGRAf.l, CF-105 J:l. L. Pc;il.lock CF-105 Item Descrd.pti0-n 1 Procur'.6 sl.J..deback V()ltm.e~:er ., ~ower mOI'li.t'ors {lil{,F and L-ban~·) , :reeord:tng .1neters, etc , ~·s tletaile:d in t:h.is repo'l'tt 2. ~0dHy AN1APX-6 (GFE) for airborne ·install .a:tfon as de·scd'bed in this re-port . 3. Operate AN/G'Rl'.-3, { GFE) ap:d check AVC t;har acteristi'c .fo.r 11ne'ari:ty, 4. ModHy and· equip e:x.is.ting .mobile . tr:ailer, prope-ioty; of EX,p~riment~l Fli~ht Test,, witb ~J.,ectrical w'.l.ringJ ·dust fiU.ers, air condf.nonin~, he:ating,., work· benches, etc • .5. Pur,cha'se two Uli~ omn,1directlonal an.ten.nas and one teJ.es.co~ing mourit ,. Purcha&e or fabricate Q,ne fi:Xad mou.gt f'or a m;r ~n tenna. 6. Plilr·ehaae or· fabricate one L-band d:-ire~:.. bional ante:nna and. J!)ount. "!. Ins,ta11 power monitors, AN/Af.'X<- q {modifi ed~ , etc. in CE-4"00 test ·/ enicl:e. 8. Inst all AN/GRT-3., AN/ A-EX-6 , recording voltmeteps, etc .• in the mobile ~P'ail'er. 9•. A.ll<;>cate 15 fiouM fl:i.ght t _ime. for CF-100 test vehicle_, UHF. equipped, f :qr preHm a.ry m~a:Su·re~en-ts. P.rograin- to co.inmeno.e ap:prox;.iroately,, Ottober 1, 1957-., Dat e Required Sept. 1, 1:957 S'ept . lt 195 ?. Sept.l, 195? Oct.l, 195·7' C .AT.£ - - REF'OltT NO 71/System§ 11/3 41'110 ~IN("N'11'°T LIMFTt:D .. ... "'1..10 ... ONT.aRlO S'MClT No TECHNICAL DEPARTMENT l ,.,. E "' '"' E"O • t ltCllAPT B'r 01'T E r..t T t>" 11 -- i.. ... , 1 v ir:'7 CF-105 A.~TENNA EVALUATION .... CtGiL\M ~~~~~~~~~"i--~..-..--~ CF-105 , ____ _c~~ -~_c_~_&_~~e-Y~~--~-o-A_t_c~-. CALCULATIOJI OF A."iTE?fNA OAI~ PUNCTIO~ W1th reterence t o P1g . (1) an etrcraft at A, transmits a e1gnnl to a ground station at $ . Since the ground station h 1ootrop1c , it w1ll be illuminated both by a direct ray e1111Snot1ng trom the o1rcratt end a ray reflected , at an angle .., by the earth's surf ace at B. The true a1~crart altitude 1f h1 and the al t1tw.te r eferenced to the reflecting plane 1a h1 • The true height or the ground station 1s !12 and the height rer erenced to the retlec t 1ng plane 1e h2· 'l'be diatar.ce ?11easured along the surface or the earth from tb• point o~ ~!lect!on to the pro~ect1on or the air craft pos1t1on on the ea~th'a au:-race is d1 ~ The distance :Qeaaured elong ~he sur!'ac• o~ the earte r:-o: the poi.n~ ot reflection to the ground atat!on antenna 1s 42 . The reflected ra~ received by the g:-ound station may be tn phaa• or out o~ ?haae with tha d1~ect ray caus i ng construct- 1ve or destructive interference. I t 1a thereto:-e necessary to opt1~1ze the gro'1:nd station height tn order to m1n1-m1ze deatruct!ve 1nt errerenee tor th• aircraft range and altitude ot greatest interest. The method or opt1m1z1ng the ground station 1s dete1led 1n th• 11torature' and is summarized br1etly below. The magni~ude and phase or the reflected wave for vertical pol.8r1~t1on 1s determi ned by -/ n2 ----( l} £. (. yn2 • coa2cv AIRCRAFT: EK 11"1?0 AIRCR AFT l /MITEO REPORT No. •p /.s¥st:ema J 3/:3 M" L'tO N · ONTARIO SHEET NO TECHNICAL DEPARTMENT PREPARED BY DATE ANTENNA EVALUATION PROGRAM CF-105 H. Pollock July 1957 CF-105 C HE CKED B Y TABLE 111 - REFLECTION COEFFICIENT FOR FRESH WATER UHF REGION VERTICAL POLARIZATION o.25v 0.50 0.75 1.00 l.25 l.50 l.75 2.00 2.25 2.50 0.924 0.853 0.788 0.727 0.670 0.616 0.566 0.519 0.475 o.433 -lBOV -180 -180 -180 -180 ! -180 ' -180 '1 -180 -180 -180 2.75u 3.00 3.25 3.50 3.75 1 4.oo I I 4.25 4.50 4.75 5.60 R 0.394 0 .356 O.J35 0.288 0.256 0.227 0.197 0.169 0.143 0.118 !t -rnov -180 i -180 11, -180 -180 -180 i -180 I -100 I -100 I -180 I It should be noted that rerlection coerticienta tor rreah water are independent or frequency in the UHF region and that incident waves are shirted in phase by 180° upon re flection by that medium. A gra~h or reflection coefficient versus 'ti ia given in Pig. {2). Having determined the reflection coefficients the ground station characteriaitca are then optimized aa follows. (a) (b) (c) Choose d1 antenna. Calculate where I hl' Calculate and h1 tor maximum gain of the ground station In this case d1 = 25.0 miles, h1 : 4000 1 • I I h1 ror the above values and call it h1 max . hi h1 2 = - d l ----------------(3) 2" h1 are in reet and a1 is in miles. 4' ror the above values and call it qJ max. ~ - cot-1 5280 d1 -------------(4) - h' l D ATE A IRCRAFT: MK AVRO AIRCR AFT UM /TE O R E?ORT N o . _ _._7=1,_/S:::..y..._s::....t.::...e;::_;m=s:;..__;l::...3u./_3.___ M A LTON . ONT AR IO SH EET No. __ A_4 ______ _ TECHNICAL DEPARTMENT PREPARED B Y DATE ANTENNA EVALUA'rION PROGRAM CF-105 H. Pollock July 1957 CF-105 CHE C K ED B Y (d) Phase shift due to path length difference is given by 0 : 1.384 x lo-4 h~ h; fmc ----------------(5) d where Q is the phase shift due to path length difference in degrees, d = d1 + d2 is the total distance, in miles, along the surface or the earth between the aircraft and the ground station, and !me is the frequency in Mc/s. For maxi•um gain Q + f: 3600 i.e. G + 180° = 360° Q • 180° For maximum antenna gain, equation (5) becomes . ( l. 384x10-4 )( 5280 )d2h~ tan f fmc 180 = d1 + d2 d2 max a d, (6) (1.384x10-4)(52So)h~ tan~ fmc - 180 Using equ'n (6) calculate d2 nnrx for ma ximum station gain (e) (f) I Calculate h2 , Calculate h2, I h2 = h2 = 5280 d2 ---------------(7) cot I 2 h2 ... d2 ----------------(8) "2 D A T E ~ ,i~/?Q "II/Cl/APT l /MI T.6/J .... ,,.. .. ta ._ ON ~ .. " ~a TECHNICAL DEPARTMENT Rl! PORTNO 71/Syatems A - ,., S tiEET "'" OA Y ,£ H. i'ollock July 1957 CP-105 ANTAHNA EVALUATION PROORAM CF-105 CH EC K E D S Y (g) (h) (i) {j) {k) For cno'aen values of d·p h a1'd uaing h2 aa determined tar ma,ximu1n anhnna ga!n th a de.f1ried region-, determine al').tenna c.overage aa followa. Calculate h~ using equ'n {3.) . Calculate "1 ua1ng equ'n (4) . Calculate d 2 and n; by solving equ'ns (7) and (8). The divergenc e factor D is defined as the ratio or field at:rength obtained art.er reflection from a spherical surfact.t to that obtained after ;roflect1.on from a plane aurfa:q.e, the I'adlateo .ppwer., total a;Xial d1stance1 and t'.yp& of surf a c.e being tn~ a~rm~ in both oa se.a, 1rnd the aolid an&le bdng a .small elements 1 angle appreaching u'ro. · Cal~u1.ate D, D • / l 1 ~ 2df c;l2 h{ d Ca.lculate 6 uaing equ 1,n f§i) -------- ---- (9 ) Determine the magntt uo·e a,nd phase of the reflection co efficient from the graph of· Fig ( 2) , Determine t he earth gain fa~tor ~~ ~~) g {e) : v1 + (DR}'2 • 2DR cos(• -f} -------(10) wn.e~e g ( e ) ia the ra·tio or the resultant field to the f-,:oee space field. trot.e that g (&) = l if tber.e i;;f· no reflected ray .. Le. g {e) ia a meaaur.e Of' the a.ntenna gain ta'k'.ing account Of' the multi path i>ropog~tion. EXAMPIJl CALCUIAT:tON f : 226.8 Mc/a We wi11 maximi ze the antenna gain at d 1 ~ 25.0 ~ilea, A IRCRAFT: EK AVRO AIRCR AFT LIMITED REPORT No _7._1_,_/:_S_._y_s-"-te_m_s'---=1~3"-/~3 __ M ALTON ONTARIO SHEET No. __ A_6 ______ _ TECHNICAL DEPARTMENT CF-105 Using equ'n (3) I : h1max Using equ'n (4) 'P = max Using equ'n (6) ANTENNA EVALUATION PROGRAM CF-105 4000 - (25.0)2 : 2 PREPARED B Y H. Pollock CHECK.ED B Y 3687.5' cot·' 5280 x 25 = 1.60 3687.5 DA T E July 1957 DATE d2max s 25 ~5 - (1.384x10-4 )(5280)(3687.5)(tan l.6°)(226.8)-180 = 0. 266 miles Using equ'n (7) ' 5280 x 0.266 h 2 max = = 39 .279 1 cot l.6° Using equ'n (8) h2 - 39 .279 +- ( 0. 26~)2 : 39.314 1 - 2 Having determined the characteristics for maximum antenna gain at a1 c 25.0 miles and h1 = 4000'. we will calculate g (e) for d1 = 15.0 miles. Using equ'n (3) h~. 4000 - (15)2 - 3887.5 ~ Using equ'n (~) rfi : cot-1 (5280)(15) 3887.5 = 2.8° I 11 NW -'111< 0 "''P l"INI F T LHUT£D ~El'ORT ..,o __J_l/Sys t ems l ';\/3 YAo L.fU.fr# O•..-T •fHO TECHNICAL DEPARTMENT S K££T k O A7 P RE P•~ eo ey DA TE ANTENNA EVALUATION PROORAM OF·l05 Using eq,u'rus (7) and (8) d2 2 ... 5260 d.2 - 2 c.t ·'P = 0.5d 2 + 5260 d2 - 39.31\ : 2 cot 2 .8° 0 39.31Ji : 0 d : 0.151 milee. 2 (NOTBa 'l'h• other root tor the above equation yields a negative ~alue tor d2 and mu8t tneretore be dis carded.) Using equtn (7) (5280) (0.161) cot 2.8 : 39.13\ I d = 15 + 0.151 : 15.151 mtlea. Using equ•n (9) D a ./ Ising equ•n (5) l 1 f 2 ( 15}2 (0.151.,.. 'OTIB7 .5)(15 .151) e : (i.38\ x io-4)(3001.5)(39 .134)(226, 8) 25.151 From Fig. ( 2) : 0.9995 • 315.4° ci- ... ArRCA,\FT ')fiij( REPO~T "°'" 71/S1•tem.e AVk O A Nl("l/Ai>T l'VITEO A8 ~A '-'TO-N - 0NT A 8 0 SHEET NO T£CHNICAl DEPARTMENT PE!E ,. Af>EO a y ! 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