~ ~"-~ V.H.F. TRANSMITTING AERIAL FOR THE EMLEY MOOR TELEVISION STATION RESEARCH DEPARTMENT. Technological Report No. E-119/2

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1 RESEARCH DEPARTMENT V.H.F. TRANSMTTNG AERAL FOR THE EMLEY MOOR TELEVSON STATON Technological Report No. E-119/2 VDC /47 G.H. Millard B.Sc. A.nst.P. ~ ~"-~ for Head of Research Department

2 This Report is the property of the British Broadcasting Corporation and may Dot be reproduced in any rorm without the written permission of the Corporation. 1 b! to; H " 1" 0 i' t (~l uut t l in '.cr-ror ('Rn('~ With R.H. (ionu~~nt P) ~HA8. -

3 August 1966 Technological Report No.E-119/2 UDe /47 U.H.F. TRANSMTTNG AERAL FOR THE EMLEY MOOR TELEVSON STATON NTRODUCTON A u.h.f. transmitting aerial for the South Yorkshire area has been built on the support column of the new 386 m (1265 ft) TA mast at Emley Moor. The aerial came into operation with trade transmissions on 18th June 1966 and started full service on 9th July t replaces a temporary aerial mounted at 102 m (335 ft) a.g.l. on the original tower. SUMMARY OF NSTALLATON Site: Support Structure: General Arrangement: Channels: Aerial: The site is 8'8 km (5yz miles) east-south-east of Huddersfield grid reference SE/ height 259 m (850 ft) a.m.s.l. The support structure is a 386 m (1265 ft) stayed mast. Up to a height of 274 m (900 ft) the mast is cylindrical with a diameter of 2'74 m (9 ft) and this section is equipped with a lift. Between 274 m (900 ft) and 335 m (1100 ft) the cross-section is triangular wi th a side of 1'98 m (6 ft 6 in.). Above 335 m (1100 ft) the cross-section is triangular with a side of 1'30 m (4 ft 3 in.). The mast stays which are attached to the faces of the triangular sections are on bearings of and 352 ETN. See Fig. 1. The aerial is designed to radiate on the two BBC channels 44 and 51 of which the latter is used for the opening service (BBC-2). Channel 51 has negative offset and Channel 44 will have zero offset. The aerial comprises eight tiers each of six SA. panels giving a total radiating length of 39 4A. at Channel 44 and 42'7 A. at Channel 51. The panels on each tier are mounted in pairs on the faces of the support mast and are fed with co-phased currents. The panels on face AB (bearing 232 ETN) are fe d wi th a current ampli tude of 0'6 relati ve to the currents in the panels on faces BC and CA. The aerial is protected from the weather by a 2'74 m (9 ft) diameter glass-fibre cylinder. Fig. 2 shows the arrangement bf the panels on the mast and Fig. 3 shows the construction of each panel. The mean height of the aerial is 370 m (1215 ft) a.g.l. Feeders: Power: The arrangement of the distrib ution feeder is shown schematically in Fig. 4. Each half of the aerial is connected to the transmitter by a feeder type F and G 6.1/8-50. Two 25 kw vision transmitters and two 5 kw sound transmitters will be provided for each channel; at present only those for Channel 51 have been installed. Each pair of transmitters will be run at the power required to give the maximum effective radiated power (e.r.p.) permitted under the Stockholm Agreement namely 1000 kw. Each vision transmitter is combined with a sound transmitter and the combined outputs are paralleled by means of a diplexer followed by a splitter transformer. This arrangement is employed so that small differences between the modulation characteristics of the vision transmitters

4 2 cannot cause distortion of the received signal. A two-channel combining unit will be added later as required. Templet and horizontal radi ation pattern (h.r. p.): Vertical radiation pattern (v.r.p.): The h.r.p. was specified to be directional in order to avoid waste of power to the west where the service is limited by the terrain. The h.r.p.s at the vision carrier frequency of each ope rating channel which are shown in Figs. 5 and 6 together with the h.r.p. templet are the averages of measurements on each half of the full-scale aerial. The v.r.p. was specified to be gapfilled with the maximum of radiation tilted 0'9 0 below the horizontal; this is achieved by means of a phase distribution of the feed currents over the length of the aerial. The v.r.p.s obtained for each face shown in Figs. 7-9 were computed from measurements of the amplitudes and phases of the feeds to the aerial panels taken after erection. Gain: Channel -lean intrinsic gain db db 15'9 15'8 Deduct aerial losses: Gapfilling Distribution feeder Distribution transformers 1ean net gain Deduct other losses: Main feeder 387 m (1270 ft) F and G 6.1/8-50 Feeder ground run 12'2 m (49 ft) rigid copper Diplexer Splitting transformer -lean effective gain H.R. P. maximum/mean ratio Maximum effective gain db 1'4 0'2 0'1 2'4 0'2 0'1 0'1 db 2'0 0'2 1'7 0'1 2'3 14'2 13'5 2'5 0'2 0'1 2'8 0'1 2'9 11'4 10'6 2'6 3'9 14'0 14'5 Programme feed: GP.O. link ACKNOWLEDGEMENTS The mechanical and electrical design construction and setting to work of the aerial were carried out by EM Electronics Ltd. The contracting authority was the BBC Transmitter Planning and nstallation Department. SMW

5 :-385 6m (1265ft) g'3m (1244ft 6in)-----j~ 370 3m (1215 ft)-----6:- ---/ Band V BBC 1'30m (4ft 31n) triangular sllction 361 3m (1185ft 6in») ' 3m (1156 ft) --u;t; provson for Band V TA 343'4m (1126ft6n) m (1100ft) m (1045ft) t---+ Band m TA 1 98m (6ft 61n) triangular sllctlon 289'6m (950ft) to provision for Band or Band m 274 3m (900ft) 2'74m (9ft Oln) cylindrical sllction with lift provision for other allrials Fig. 1. General arrangement of aerials on mast

6 cylindrical fibra - glass waotharshiald N c 1'3Bm (4ft 61n) rod. ~ '30m (4ft 3in) F.ig 2. ArrangClmClnt of U.H.F. aclrial on thcl support mast.

7 310mrn/f"j (1ft Oi-~) 560mm (1ft.10 in.) 2 23m (7ft 3~ in) 101mm ( 4in) Fig. 3. Construction of eariel penal

8 B - main feeder Fig 4. Schamatlc arrangamant of distribution faadar (owar half aarial) o ac2rial panc21 with rc2lativc2 currc2nt shown cg;:] transformar

Flg.5 Horizontal radiation pattelrn: Channell 44 HORZONTAL POLARZATON Vision carriar 655'25 MHz Sound carriar661 25MHz Maan affactiva gain: 11'4dB --Stockholm E.R.P. limit Paak vision transmittar powar: 2x20kW ---Additional dasirad E.

9 Flg.5 Horizontal radiation pattelrn: Channell 44 HORZONTAL POLARZATON Vision carriar 655'25 MHz Sound carriar661 25MHz Maan affactiva gain: 11'4dB --Stockholm E.R.P. limit Paak vision transmittar powar: 2x20kW ---Additional dasirad E.R.P.limit Maan E.R.P.: 545kW Minimum dasirad fiald Unit fiald corrasponds to an E.R.P. of 1000kW

10 Fig.6 Horizontal radiation pattflrn: Channfll 51 HORZONTAL POLARZATON Vision carrhar 711'25MHz Sound carriar MHz Maan affactiva gain: 10'6dB - -Stockholm E.R.P. limit Paak vision transmlttar powar; 2><18kW ---Additional dasirad E.RP. limit Maan E.R.P..' 405kW Minimum dasirad fiald Unjt. fiald corrasponds to an ERP. of 1000kW

11 "0 ( o g 0'8 0'7.t:.. Cl C 01 L... Ul 0 6.~ 0'5 01.~... o 01 L. 0'3 0 2 o 1 jf 1 ~. ''' - ( 1 1 '! ~ ~ :j ' 1/ ~.~ J / / 1- "... ~ ) 'J '7 ~ ;-.. lj 1' L_ ~ anglcz balow horizontal dagraas approximatcz ranga km Fig.7 VlZrtical radiation pattlzrn on blzaring E.T.N. (sidlz CA) Channczl Channczl Spczcificzd minimum ficzld

12 1'0 ( o g 0'8 0 7 s:. +' Cl C c: ' +' U) 0 6 "0 0'5 ~ c: >.~ -; ' o 1 - :/ 1' ' ' :j ' 'V '-f l j ) j " ~ "- 1"-" '( / / ~ 1-1""<:... ~ - r- _ ~ r'~ '"' J. 'l/... ~.1 - ~- - 1' t- _ -- ' (lngla balow horizontal dagraas 20 " approximata rangakm Fig.S Vertical radiation pattern on bearing Chann~ ChQnn~ Sp~cifi~d minimum fi~ld E.! N. (side AB) -

13 1' '7.s::. +' 01 c: (j 1- +' Cl) 0'6 u 0'5 (j (j > :;:; a (j L. 0'4 0'3 0-2 o 1 o o 1 '" " '1.. /... " f "/ ' 1 1 ~ '-7 ~ vi : ''{[l L 1 X /.. r " ~ r-~ 1" J '.. ~ - J '-' r--_ "- --r ~ angla balow horizontal) dczgrczczs approximatcz rangcz km Fig.9 V~rtical radiation patt~rn on b~aring E.tN. (sid~ BC) Chann~ Chann~ Sp~cifi~d minimum fi~ld

14 Printed by BBC Research Department Kingswood Warren Tadworth Surrey

U.H.F. TRANSMITTING AERIAL FOR THE SUDBURY TELEVISION STATION

U.H.F. TRANSMITTING AERIAL FOR THE SUDBURY TELEVISION STATION RESEARCH DEPARTMENT U.H.F. TRANSMTTNG AERAL FOR THE SUDBURY TELEVSON STATON Technological Report No. RA-152 UDC 621.396.712 19689.H. Millard 8.Sc. A.lnst.P. for Head of Research Department This Report