V !

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•

Research Department

IJ;lvestigation by: .... O. j?GeoghegaJ;l .•

RlEPORTNo. K.058

Ser1alNo.1944/4

"-,

nm§TlGATIO~r,OFTH:E,:,MOD!FICATI6NS .,. TO • TRANSivttT$

l?OJ:.Ah DIAGIW5RESULTmG FRO~ THEERECTI6N>oF,

THE BLAW-KNOX:~~T.AT DROI'lWIOH.

SUMMARY, . -. ,h" .. ',' .

", . ... '

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. :lpl.~ B,law-knoxmast·radiator.was erected at Dr'oltWich. fPf #q.iatin~the 26lm~~re:<European ~ervice by vertical polarisation,' .in ~~~. Cl!,' the hori~O'rit~;Lly polarised.system which had been in use since!~'~40.

, ~ .' - .' ,. ..". . . '; . ..... - ,"

~is:repor:t:gives the results of field-strengthmeasuI-~m~n.tstaken:~n· the '9x:l,sting +lome and Forces transmissiqns, and shows that cqnsi,d,erable ;_. additi':'llaidistortion oftheZ9l m. and29bm. ,po1.ar.d.iagr,~s~Ybe·,c,~~sed 'by tl+t;l<~f~Y'J-KnOX ~stwithcertain base impedance Gonditiqp'~~ .~efln.al' condi~~o~: of conhection of the Blaw-Knox masti, Which was.~r:#ved at, after experiments had 'been carried out· to cure c.ross.-mOdulatioh.~ffeetsbetween the 29+' 'Jll~transmissionaridtheHome and ]'orces· transiriis·sl,o:q., gives polar diagr~.ms fo+ the Home and Forces transmi tt3rs not gre~ tlyd,.~tfel'ent from tho~,eEl:i:istin.g before tbeerection of tb.s Ill?sto .' .., '., .'.

The 261 m. polar diag~mClf' radla·tipnfrOlT,theBla:~-'Knox mast .1 tself ' ~sadversely ~ffectedby theot':n.erniasts·an{l aerials: on the s.1,te •.. ;",.,., ':i:~ EXpe:dments are described,whichatte.lD.pted. to effect an \impr'6vement:lii;~ome

/ directions but were 'unsuccess:f'uh' . ,It is, concluded that the only . sat i&.- . faqtory. method> of ,improving tl1~ radiation. in, a sout~~easterlyalld 'sout~e.rly directionwoulclbe ei therto re-site the Blaw-Knox mst or to use :ariothEh."', aerial ;t'6r·.thi~ serVice.· . ' . .... . ., " '. , .• '. ' .' .'

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1 . .. ImROOOOTION. .," ....

The investigations w~r~condllcted.b~tweenlst·Decetnber 1943 and 18~hJanuary 1944, during'wllidi,time the ~f'eeder arldnis.tching c ircuiits to' supply the Blaw-IOlox :ma~twer~ insta.lled~nd the cJ;1angeover from· hor~.zon tal t6vertl~al polarisat16n:tookplace. 'Thiswas conve;n:i;ent. as 'it provio.sd th,e oP~o·~tunitrforme~s~r~'iUe~-tst9.,betakep.o~:1(l1e .29Q m. and 3?1.~. d' 'I" t:t'ansllU tters Wl th. the ,E}l4w-+lliox mast present;lng' tl:tl:l' erll'eme condl.ja9nsof open cireuit and short cj:rquitto earthatthesefrsq,uellCies. In ad.dition,

"low . power: radiati'onhlea'~urements on the Blaw~Krl.ox mast accuratelyfor~t'old. 1;i;l.e 4~stortiori to the service ~r~a to'Qe exp~~rted ,a,.n&suggested1ih~~, ",. .,' laCk of success later' encountered in attempts to obta.~n ~nYWorth,wlii~;;' '.

.' " .' ".,.

improvement 0 ,~

. " '2. : PRESENT ARRANGEMENT ~

• " \.,

The main masts support betw~e; them two horizontal d~poles which were used for,l.'8.diating the 261m. service. The upper dipOle and associated down leads are also employed. as a T-aenial t.o radiate the l500m. se.rvi6-e. The Ej.erial matching circuits .for·each frequency are isolated by rejectors, on the aerial side, frOm inte.rference .at.theotli1:lJ;' ;tI'eql,lf3AGY arid in·.addition .the

, \

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balanced 261 in~ matching clrcuitb.as ac'eIit:J:8 point .. tap:p.ing~ to earth through .~ a series accepto.r .circuittuIlea:.to,·3~1 .tii~ .. ,:., .... ;: •• i •

, ' . " .," H.', ~ ••...• ~. • ..... :.,' .....

. . " . The 2$6 ,m. a.nd 391m. ae;c:i.~l.a;~r.e;susi,encled .frqn(: ;r;i.~t~csa ttached to the N?rthMe..~~.~:~ili~!~t'he296 m. aerial match1rig cir~Ui t:~'~have reject~~:'\;'··'·":~~pt.es .. tor 264 .. m, 391:m.and 1500 m.· The 391 m. cirCUl t has on1Y>EI.,)1ll ....: .• l"ejector and oI;le·t~e.d:tp'!34~ m •. remaining from the time the station,;-ad~~~~d the

. Forces ~grarinneon that wElvelep.gth. . '.' i'

.•.. :.- ...

The Solith Mast has an aeria1 similarly suspendedby a triaticwb.ich was' previ'ously used for radiating 373 m~ a.nd is .nowdisused •.. ·,· .

. . . . .

Bo·th main '~sts have a 261 moacceptor to earth at the.:base. These e,.cceptors·had been installed for. the purpose 61' Hmi tingthe verticall::" pola!'isedl'adiation from th~ mastsQ '.

". '. Tb.~ Blaw-Knox mast· has 391m •. and 1500 m~.i'ejector circui t~ at its base ... ,a.:tld, a 29·6 m;. acceptor circuit 'to earth at the' .input to the feeder trom the

261m. transmittercoIT),bill.ing .olrcui ts J and at· the point where thefeedeI' enters the A.T.·H. '. . , .

" . " :. Ii::~r' .. " . . It;wi:Ll .. be.seen from the diagram (lfig.l) that., the 391 in. and: 296 .Jl •

. aeria1s . .:11e along the: same line' as the" Blaw-Knox' on a bearing approximtely 200 E. of N .

.... 3. . 296 ·m~SERVICE . . -"., ". ' ,

The 296 m. and 39;1 m. aerials originally fomed. the ~adia.tor and. refl'eator of the Midiand Regional a,e.rial. System a:r,td 'ar'e oriented' on' a bearing 200 E. of N. to give an increased signal in ·~b.e.t. direction to serve the Midlands. In wartime this'area is still dependent on. the.f?erv~ce on 296 m.

wavelength for. the Forces Programmee.:ild the aerial system had a gain of 2.8o.b. in that direction over the me.an·rad.iat:i.on(Fig. 2), befc::?9. the-erection of the Blaw-Knox mast. .' .

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Since the erectionof~the:Blaw-Kno~ mst;'.I'Thi'ch·is situated·d.ireatly on .thi'sbearingOf· rnaxi:nru.m require(l radiation,·tJ:i~gainin this. direction relative totj:te mean field:"'strength has fallen' toapproxitnately unity; " The. ,effect: of 'fpee1ng or earthing' the'Blaw-Knox rl\.ast had littl~effecton ·tp.e

" se=:~fce exceptiri a N.E. and N. W ~d.ireGtion, 'whereearth~ng the mast caused an increase ·of·3 db. on a bearing of: 60°' (tqwardsCoventry), an.9- a decrease .of2~5· db. ·0:n8. bearip.g of 280°.:':: (11g~ 3.·r Further invest1gati<:mwhen ..

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the i'eederand ~t~hing circuit to the ~Blaw~Kno;x: 'inast'w~recompletea shb.~d';' .:that :the .?96 in~polar diagram was scarcely affected whetlierth(3,~npu,t~~~,,"!ihe . Blaw~IUioi: 'teeder was earthed or. connected', to the 26lni. t~nsmi tte:r..,., .. tJfe~e<: .

; " , ,', . ' " " _' " , '..' " , .' , ' • , • r ,.... ,~'" ~,' ".",', ,",... ,", "

geIleral shape being intermediate between ,theea,rthed and' tree~condi tion'oi'" .. tl:iemast' i tselt~. . The . tinalpolardiagram '''i tll a 391 m. reJect'or,and 2~6i!m •

. a:c.ceptor inthsc'Blaw-:-Knox A.T.H.aIid a 296 m.acoeptor .intl.ietraI1.sm~ tt,e.r .,,' matching circu1:t;sj, is"Shown,in Fig. 4. ., ., .... , ., '" .... " ·;<~.,L:'~r::;·'·;

.• , ·~oattempt·~~'S:'~de·to:~prove.the .. radia~io~;~ha •. south:'e~~~:;~t~~'~~~~~;lY ~1i'ection,which appears to'be adversely ,affected by the m1n'masts,:)is:S:iiy, likely 1n6reasewouldnot be sutticie:p.t .toremove the OXford-SWindon district

'fjiom th~:musharea, and would at :lihe same time contract the'llo+"tn~rnmost' pOrt1C?,n Qt/tl+e'~sef'ul'serv1ce area ot· Fareh8.ift./' 'It .~I3 .. i.n.l'),;l~ :~;;o~betWeen 20° an~6q9 ,'E;, of:N~)hat. radiation israthe.r"lessthanJt,~as"~~:t'ore the ereot'i9n:'ot' :the 'Blaw,,,.~pxmast:. ' '. .. .

"", ," /' . ' .,.: . .,'.,: ..' . .' ,.·C',:': )

". 'Finallymeas,urement's .we'l'emade oniowpowex' radiiatingf~+'p~; 1;he :aeria'lpn theSou~h mas1!to!see i.fany ; improvement would result 'it:: :the;'~~6;.m. service was t+'!3,.J:ts'r~rredto.i t. This2gaveamos tunsa ti stac tory pol~:c q.iag~(lI'j,g:.5 )

J,,: \;;1-thtli~~<liatioli largeIY''goIl~en:tratecl between 500 and':200~:~!9f .N~ .... 'rh.:ts •. inY~st:i.gf1t:),Qnwa~' notpur~ed .. further. ' . "",: .' i.'; .••

. " . ,;Th~:er.ec·tipri· otthe"BlaW'Kno;x:;mast' had the ~ffect on· t:p.iswavelength:'a's '. " i,)n:,2.~H; ;ii!.,O,f.reducing ,the. north easterly radiation when the· ~$twas .free,'

. ,':; , "w:h:tle'~h~ ~arthing ,otthe mast o'aused a serious distortion qt '~4e polar. . ;, d.iagram:tow~rdsthe S,.E.' and N.W. 'directions as well as reducing the'N.];." " ,.'. r,adlat'ion '{Fig~' ~} .. ' ,Asi;heBlaw~Knoxma.st remained ea:r;tlled 'tor prao:,t':t'ca.~:j.y .

the \~holet-imebet(j:re it'wen,t into service, this period of ,.s,eriou~ :'di:'2:lt;9~:i.q:q. .·was .conSiderable.' '. ." " '. . ..... " • . ." .. : ':, :.,~~;t.'" , ..

. , . , ' . " .... ,_ ", _ ..... ', .. , '~",. ", ,', -_ """", ,"', ., .,: ,:~,~:,-li}:i', , .... '··.··Two more polardiagram~were1neasured when thecb£lnge. over., of 291:'tn",:.to:.:·

the Blaw-K'no;x:cradiator Vias abqut totakE?plac~. . 'J;b.ese~owed·tp.at whel)'>,~l1e . '. Jnput~.endotthe feeder . from the combining iiouseto theB4w':'Knoxnlis'-\; :~~'I'~H. " ·wasea:rthed,.or·freethepole.r' die.grameiresul tins were' similar respeotivel,:yC 'lio

.. " 1,~liose:,Qbta1ned':wlth'the mastearth.€ldol' free. .'.: ~"'" '..' ····':.'r;;,'::;,!: • ~ ;:, '. ,; .' '0-'. • .",'

~ :-. r,.~ ,: ",' , ,,' .',', ',' ':."I,,~ _ ,,' >,' " ,:',', >. <", •• ,.:'-F:.\",.·/::~h~5~;~:~~~j'~:::, '..' .,' " Whilet~e 261 m .. ,t raI}.smi tter., wa,~'radiating ,the: f~ ~der,C0itilecte dto.:i: $.~e "

au tpu t· ot~the ~rallsmi:tter and1;~e:po.lar diagram resembled ,fig It, 6 (bJ~ ::o..¥t~#g, the . daylightshut~down .period however, . the . feeder. was. removed froI]l,the.:: .' t#nsmitter Qutputcircuit a;nd ~rthed:at its inpu't eIl,d producing.a~PQ:I;~J::,;

. diagrwn similar t.o· Fig. 6 (al •• ', The .Home ,SerVice 'Polar diagram wEis,def'~ri.i tely UIi~ati.sfactoryundei'these cqI;l,di tions during periods when the 261, m~ trcms-. ". rn:i.tter was hot' ra'dia1iirig. . ,. . ::~"'-> ; .' " 5.INTRRFERmOE . FROM THE 26i"',mi . rmANSMISSIONS '~$:Jrdm ANDFORCESq~c,~" .'

• <', " ::'., . ..... .' .' ....... '.;~.' ~,' .... '. ·.:m()d1~Al~~ ~".:' Report'sot interi'erelic~':h~~r~eri the 261ril. arid~Qme ~d ForcAsServl,?l@:J.

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transmitters producing a ,backgroung, of European Service on "the·Home and Forces programme led to investigations which showed that some voltage from th,e39l m. and 296 1ll:. transmi'tterswas fed baCk to the anodes of the fiooi stage of the 261 'm. transmi tterand ,was being "fe~radiatedmodulated wi ththe, Europe'3.n progre.miRe.' These lri:vestigations bave been described in;!;d~ta.~a in Report No.,A.012~, In the 'oase of the' Home $ervtceon' 391 m. ~tem:P9r~rycure was et:fected: by connecting aJ:} earthed acc~ptor (tuned, to 391 m.) a,t the inpUt end of the 261 m.feeder.This cut down the"local+y generata:d~llterferetJ.ce but resulted i¥ the Home Service 'polar diag:ram :be'ing tll,e s.b.8.pe:slJ,Qwnln F1g.,6(~)

" which is v~~.I 'Unsatisfactory. ,,'rhe f;3.cceptor yms later rep~ace~·J;y'e,3.91 m. 're~ectp~~lti, 'led in, the Blaw-Knox\A..,T~~.to give, thepreS6A{,'" "';:d~EhSram pt'<r;s,.::j~;,~\,,<!}l~.i.s"~~ sati~.f~c.t,ory, ~s ~he best qf the pre:v:~~{, ;,,,,,t~, and

" in,ra~t,'ln.dst 'ru?ar!Y.,reprfjsel1ts, the, co~dl. tion, b~fore erection;Qt"".:the :Blaw-Knox ma.s1;~The:tel,ssonie gain of radiat'ion. (2 dp.) in the N~lC,.di.rection. Qver the meanval\l.e,. as compared with Fig~ 6(a) at the expense of' ·theS~W.

,rad1':ttion, iiiwh:}ch direction the normal service in outlying,'districts is 449 m. 'from Washford.' ' ,

.' '. . " . , .

, The; instaJ"la ti~n' of the iuppressing the interference Servicetranslniss~on ..

series 391 rejector W&I;I c0h1pleteiyet1'e6t1ve in from the 261 ITl.transmission (,n, '~he,~9im. F..ome

,1.. , ,,'

In,·the~·,(,a.se"~f.the interfe~~nce with tb.~ Forces. programri1e On'~96.2· ' metres, it'W'asnbtpossible to install a series reJectpJ:'in . the aer.1al bircu1t of the Blaw Knox mast owing to the sIT'B,11er frequency'di:rferencebetween 261 in.. and 296 m. ,An earthed acceptOl'1A'US therefore,t:J:.'ied at .the inJ?u,t end of t:qe 261 m~ feeder ln theriE::tn, combining 'house. The degree ,of suppression' ob.tained by th~,s method was insUfficient andfollowip,gsome ,t~sts carrie.d out by S.D~ I .D. at Prol twlch an addi ttqne,l acceptorcircui t,'w8.E;(installed ,in thA, Blaw-;rcnoi A. T. H., between the Inc·om.illg feeder and eaJ;'th. ':' The effect of this has, been to suppress completely the: interference wi ththe Foroes progralfhne and listening ,:t,e,sta have been carri'e,d out in the Birmingham district which oonfirm this."'" ..

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Finally low. power 'measurements of. radiation from tlie South Mast aerial . 'r··.' ' ,. were taken for, 39l.):n:. '. ' The results ,cor:re.cted to the same 'mean value are shoWn in Fig.8, comPared with the present.diagram (Fig. 7 )' • The pronounced

,N.E. lobe of radiat.ion would ,be more advantageous it its peak lay in a more northerly direction; bu.t l,i;W'ould,CilIltail adI'op 0:' 4,.5 db. to the north vres~, with possibly anlinsatisfa.ctOryse:CV1c:eto :gerefoI'd .and ~opBh11'e. It would therefore not bs\ desir8.b~e to:~jia~~'t:p.e39l m. ,service over to this aerial. . . ' "."

:": . .,. \."., "

6. 261 m. SERV1dE~ . ~ '.

,'The .Bial'J'-'IUlo:+, mast. was constructe,t' .t6 Provide El better service on 261 m .. ' . ,to the continerl:1i':'o:r:Etiia6pe' thanwaS'oot"ined"'fronl the ho:rizantally'polaris~d

· .. :::di.pOlesusedp:reviously, .'I'b.e. extl9nt .ot ,'the .area to be ser:ved lies ~oughly . . in' an: arc between 400and 1900 , 'the"bearing'S' or Oslo and ~drldrespectively. '

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Radia,tion in any: direct10iloutside this arcis,th~re:t'o:~was:ted~ , :Th,~.Bi~~­Knox mast, however,' was .intended to opera-teas a:siilgl~,n;Jas't rad~~:t;\?t?!t~hout' any intentiona:ld1rect~:ve properties. ' :. '.

~! _to '.

'A polar diag~ measu~ed" onlcw power before the£ee'der~n~er~!in4~11ad was later ,c.onfirmed,bY measurements on tull power '1;0 g:iVi th~ q.istr:\:bXt'tlo~ ,

. ,''''', '. .' ..... '. .' . . .". .... .,' I ... ' , >-

shown in fig.9, wb,1c~.sh6WS,a~an value 'of :t'i61d~s~r~1l~.tP: at 5 }an~, b:~,:' . 10].5 mV/m; andf'or the. arc 40 - 1900 ot 970 rnVjm.{TliemaximUI!iradiat'ion occurs @fortunatelY-in tile' unwanted directions ··ot2700 ,and:3500)." Mitiirinhn ,raCtJationisin a direction 1800 and is 6 db9 (lownonPh~ mean;' over most', 01" the sector 40- 1900lvariesbetween + 2 db. at 750~'iuid -2.4 db. at 1150• . .... the radiation . . .' .' .' ", , . ,

". '~~~e~lrl.ation·ruIlswere . taken or; full' power, :t'ig:'l:0, :'P¥ '!l~~~ ·~earings . spacea~1i, :J.20o,.a.nd from·these it lS possible to:,cal,.G.'Ul.a'~ t~e mdJ,ated ,.powel'!'~d ~d.ia tion.efticiency. ,Thel three runs,' sh9w~!allaYe~ge ~duction

fact0l:' to;U$ km.of:O~835~'and the following tablet givesotp,e~ 'fmportant. data "1.' . ,'.,' .. " .. ' .

... ",:'.,

'.'.':

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Mean, Ed. at 5', km., ' ' ',:: .

Mean,~od.o

Aerialimpeaati6e ~ • • , >; • .:;.... <

'" ,'Ae~1a:l .• C~'r~~rit:" " .. . .. <-~: ~ -, ;.: ...

. ,0 .. Aerial i~pi.i'f-:power . . : '. " . ~( :-.", '. ::,,' ~. . " . ..!..i.

. 5075

6100

~.~. .-

106 -+ .jO ohms '.

'SO,amps

380 kW.

360 'Approximate Eodo/l1{j. . .. . radiated (Fronl.' theoret- .

lcalc\lrren~ .

....... . .....

','. ;0-"

"~"."i- ,,' -'

r ',/

,::," .

·· .. ·f" CJS,dist:t'ib4tion)

. ,',"" : ~',l.~.

'.'

, Povier i>e.di~ted ",

'. 'Radi.attone:t'ffc :i.enc.Y·

. 290 kW~.'

7fY/o :'" "

'~.:J<~~.' ~~;; ; ,. \ '. :" -'i --

'l,'p,e'polardlagI'am ShO\'l~ thatre:(Ue.ti6ntot~esou,tha.Iidto a~rior,eit~~(,': sOu..:1!b.east . lsthe leastsatis:t'actoIT. . Exc'ept lO,r ,tl1.edi:t'fereJice' iIl.s~~e.):,pf

,tB'stWo soiJ;therly 10beso:t'Fig.9, the diagl'amshows'a tendencyt6 sjnme.try about an aXis. 200 E. ofN,tl1e Id.pproxima teb~ar~ng of the 'Blaw-Knox J,naJ:;l~. f'rom the Home and Forces aerials" . " fl'.b.Be:t'fec't·ofvariQti:~" tests invol.V,irig'· ea,r:thi-ng andfreeiI]g Of the '700' 'maS,ts ana, the 'aeri~s:Qnthe:t'iel<l·;:stjfeIl.g~tih OIl bearings of 1140 and17So :t'rom thestatiop,Gorresporltllngwith't:woJD+P:ima sh6Wed that Undernocondi.tioIiswas there any grea:t variation. Tb.ema'sts

'. are rior,mally eai'thSdthrottghacceptors at 261 m •. an,a:changing the te~nat·· ionnede little change.· Earthing or freeing, the horizontal dipoles was . eqUally ine:t'fective. E&rth~hgboth the Home and. the 'Forces aerials; Which

" "

, . ~ :

- 6 -

,s,re ~:r,'est to ,thi9:e-iaw,,-Knox "mast' d.fd;however,:causee., small:inq,rea.seof 1.5 db. in a 'sout:tie:i:'1y'directitm~' 'Fig. 11 is'S. pole.rdi&g~am.o~ the 251 In. services with the Home and Forces ae;:ria'ls earthed." ~'I:t "shpytl;! no " generally ill1J?ro.ve.dradia tion within the reqilired' aro as oompa:redwi th Fig.' 9;, the changes b,e:(ng of no great im;portahce~' "".,

- . . .... , \ ',,;,' ,.,.', " . "':;~, '":" .:~ " .:.. '

. "rine laok of success:"of' 'the, ab;ovetests showedthat:no, itnProvem~nt ls ,obtaina?le ill: the'polar:d:!:agram sbape"f(t'om the Blaw-'Knol: ~,<l.~atoras a result 'of an~,si:mple a1 t~ra tion, t'o the, other,lrj8.stfland ael'iaJ,.s :on.,t};J.~, site', :, $ueh as ,theJns~~;q:ation,!ot ,a~G'eptors or',rej9cftr6rs.' ' It appears""~o~tunatel¥,, that the si 'tie ,:pf; ~ ~,~e' Blaw-Ifuox l?8.diator is 'not' ver.y,se,:t1sf,ao.to:i:-y'h~V.iri:g:iresa.l:d tlb

, ,the req~1~g~I';4irections for the European Serv.J.c'e'~ ,,'~ ,.'" ,:.l;i!#;Uj:iii;'i', " :. '" • ", ," ~ !Ri. 1" ~ ~t ',,),~ """. :. j'" ~ .' .. :.: !~:" . ,: ~' .!, ;'i4j~T:')? ;~dhl~~.\j' :., ~.: \:

:";7~: .'1560'm~ :SEltV!C;E'~ .""._ ..1" > ';: <~ . .' ~

':':. "''lh~': p6lardi~g~~'f6r this. 'wavel;ength 'diftered"v~:ry>'~light~Y from the oiroular before 'the erection of the Blaw Knox mast. The presenoe"o:t' the Illa'sthas oaused a small decreaSe apprOXimately' due llor.tl1~- thedireotion ot the mast', but in other respects ha.s not modified the cirole (Fig. 12) .

• CONCLUSIONS • :', -, '

The Hom:') Service (391 in.) and the Foroes Service'(296 m.;) polar diagrams are not seriously changed 'by the presenoe Of', tb:a"Bla:W"'KnOx radiator for 261 m. wi th its present A. T.H. network.' The Blaw-Knox mast ~should not be earthed during Home and Forces programme Umes 'unless'thd.'si.s;'9s,sential for urgent maintenance reasons~

"':

The 1500 m. transmission is'·'subs:tantially .u:riaff~c'ted by the new mest. The radiation distribution on 261 m. 'from t1l:eBlaW7"Ktlo:x: mast is adversely affeoted by the other masts andaeria.ls on' :thesi~e:.' It appears that the only method of improving radiation in a south-eaSterly and southerly direotion woUI,d be either' to 're-site the mast:'1n/.fl, niore"southerly position or to radiate the 261 m. traD,sndssion from a new aerial suspended from the south mast and arranged to 'giV-6 a pOl8.r:d1a.granCfavouring the required directions fro:gl east to soutp,. . ,

. VDt~.

\ , .' "~ .'

, ...• ' ;·.t.: '

.,,' .

.. '

;': .... J¥~:r .::;

(A. ';B.:,Pl')we;. tor :S:"R.D.)

.. ',.: ", ,,'

, ,

'.' '

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DATA SHI:t:T NO. 13. CIR U1.AR \POLAR) CO-ORO(NATIt. WIG1-CTMAN MOUNTA.IN LTD • ARTI.l.ERY HOUSE. AAT.u...ERY RPW. W S M NSlliFt. S.W.1

O,",TA s .. ~ 0. • ROt .. C'''NTRAL lieu • 45 t<JNCiSWA f. "C

6001

DATA 8HIiCT No. 13. CIRCULAR (PoLAR) CO.OR~'NA1-.~ WIOHTMAN MOUNTAIN. LTD . • ARTIU.t:RV HOUSE. ARTIt..LILRV Row, WItSTMINSTER . S . W .. I.

DATA SH.-I!T NO . 13 . CO· ORDIN""S. CIRCULAR (POLARI -

---------==-=~~~~M~OUNTAIN LTD., S.W41. WICJHTM4N ERi RoW WOTMINSTER. ARTILLERY House, At'iT.U ...

DATA St4£1!"1' NO. 13. CIHCULAR (PoUR} CO·OROINAT". W/GHTMA.N MOUNTAIN, LTD • ARTILU';RY HOUIiE'". ARTll.!...ERY ROW. WESTMINSTER. S.W.1.

O~TA. SHErI' No. 13. WIGHTMA.,.. MOU"'TAfN·~::';';"'I""STER. S.W.l.

A.RTIL..L.Elty Row, ARTIL.LERY HOUhe:. •

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DATA SHI:JCT No. 13. C,hCUL.AR {POLAR) (:O-OAOIN"TI.; W.GHTMAN MOUN"'~IN. lorD .• AFtTt1..LRRY' HOUSE. ARTILLERY ROW, W£STMINSTE,ft. S.W.'_

FiS.

•• OT..l . \o1IAT~UOM KAMTHOIW / .lTA\o110RO-O:l (MA.JOq) RA-JU::>RI:J • £ r .0111 nt ll UC! ATAO .. f. W.2 .fl3Ta""IMTa3W .WO~ V~~.J~ITR.A .3E:UOH VR3I.J,JITAA

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10,000

10,000

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O"TA SHECT No. t3. CIRCULAR 'pOLAR CO.OfltOINATIL. WtGt-rrMAN MOUI'IITAIN. l TO •• • ARTILLERY HOUSE, ARTIf_LER" ROW. WUTMI~ST£JIt. S.W.l

O"TA SHItICT N~. '3. CIRCULAR POl..AR] CO..olltOJNAT£. \NtGHTMAN MOUNTAIN , LTU . • ARTll.L.ERY HOUSE. AfltTll.LEAY RoW, WaSTMINSTER. S.W.l.