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Military Early Days

Page history last edited by Alan Hartley-Smith 2 years, 4 months ago




WW2 Military Radar Systems 1938 to 1945

These were put to the test very shortly after the declaration of war during what became known as the Battle of Britain.


For the moment this section covers only ground-based equipment - yet to come is the equivalent for airborne systems.



This covers the original metric floodlight radars with separate transmit and receive systems, for which Marconi Wireless Telegraph Company Ltd. designed and produced arrays, also masts, for the later systems, and early combined systems for which Marconi designed and produced elements up to and during WW2, followed by the move to centimetric systems with the development of the magnetron. The CH and several other transmitters were designed and produced by Metropolitan Vickers and the receiver came from Cossor. Metro Vic eventually became part of Marconi Radar Systems Ltd,


When the Air Ministry's radar development team was established at Bawdsey Manor in the immediate pre-WWII period it was initially given the name Air Ministry Research Establishment but on the outbreak of war became Air Ministry Experimental Station (AMES) Bawdsey or AMES for short and this acronym also became the basis for naming RAF radar systems through the war, hence the type names in the following list. The numbering continued postwar.


During this pre-war period the scientist leading the development team - the then Mr. R.A.W. Watt - proposed the establishment of a new RAF signals unit to be responsible for the radar system and this eventually led with the outbreak of war to the formation of No. 60 (RDF) Signals Group which went on 24-hour watch on Easter Friday 1939 and until finally stood down in May 1944 - its history can be read here.


There is a comprehensive listing of a number of the shore radar types here


This early radar development was one part of a comprehensive approach to the defence of the United Kingdom, and it is appropriate to include details of the other parts as the Marconi Research Laboratories were heavily involved in the design and implementation of what became known as The Dowding System which was at the core of the 1940 Battle of Britain defences, also in research into devices for radar systems.


Inevitably interest grew in designing radar equipment to fit into an aircraft to faciliate interception of enemy and this branched out into a separate arm of the research unit. 


Editors note The 2020 Battle of Britain 80th Anniversary celebrations resulted in a series of commemorative events, including a lecture by myself as part of the Chelmsford Civic Society local Heritage Open Days programme which has stirred interest in related Marconi connections details of all of which can be found here.   


An early set of articles in Wireless World - Radar Production; Radar Fundamentals 1; Radar Fundamentals 2; Radiolocation 1; Radiolocation 2


Interesting story about radar deployment on D-Day









Power (Peak)

Pulse Width











12.5, 25, 50


Figures for later modifications. Earlier systems had 200KW and 800KW outputs. Some systems designed for 42.5-50.5MHz. First experimental systems used NT46, then NT57 Then BTH Type 43 or 45 Demountable valves. Earlier stations had powers from 450-750Kw. T3026 reported as 450Kw, 5-40uS; T3026A 750Kw. May have used transmitters from MB series. Could do Height Finding from 1.5 to 16 Deg. Targets lower than 1 Deg are not detected.






                                                                                                         Original caption

CH description

This link is to a paper written by Bruce Neale and first published in the GEC Journal of Research


CH description this link includes a paper written by Mike Scanlan published in the GEC Review


The CH Radiolocation transmitters - a paper written by Dr.J. M. Dodds and J. H. Ludlow.


Post Office Equipment for Radar - an extensive description of the calculator devised for the communication of a map reference position, the height in feet and the number of aircraft.


CH - Wikipedia


IWM entry


An interesting item of heritage


A personal memory


Isle of Man installations


CH Tower at Baddow - this was originally one of those installed at Canewdon and a presentation about it is shown here courtesy of Andy Tyler.


Ex-RAF Aerial Erectors Association - this site has useful information but the dates given are widely inaccurate as the initial masts for the East and South Coast stations were wooden and erected by government staff. The familiar steel towers came later, when curtain arrays were mounted by Marconi staff; the West Coast stations used guyed masts of Marconi design, all most likely to be 1941+, and the standard wooden receiver masts.





Much documentation about Chain Home, Chain Home Low and Chain Home Extra Low installations is not correct - for the best descriptions and accurate details of all these installations consult either "RDF1' by Michael Bragg or "Building Radar" by Colin Dobinson.


Notice from Historic England - 24th October 2019

Chain Home tower at Great Baddow, off Vicarage Lane, Great Baddow, Essex – Awarded Listed Building Status

List Entry Number: 1456445

I am writing to inform you that the above building has been added to the List of Buildings of Special Architectural or Historic Interest. The building is now listed at Grade II.


Other surviving towers

Swingate (Dover) - Stenigot (listed) - Gt Bromley - Dunkirk (listed) and Northam Devon (buildings)


This painting by Chris French G.Av.A. shows three steel towers with their transmitter antennas slung between. On the lower left, the "girl on the tube" interprets the "blips" of enemy aircraft on the screen. The information was then sent via the telephone (lower right) to filter and operations rooms where the table-map could be updated by a "plotter" (top right). The markers represented hostile and friendly aircraft and were used to plan and monitor air battles. 234 Squadron’s Spitfires (top left) peel off to intercept enemy bombers. The succession of functions became commonly known as "Read", "Report", "Filter", "Identify", "Tell" and "Plot". Click here for a larger version


The performance of the complete system was formidable - this is illustrated by this clip from the Associated British Picture Corporation film "Angels 15" which shows the sequence of events from detection to takeoff in real time.


1935/6/7  The success of the first five CH stations  promoted the ordering of twenty more. For later stations Marconi provided and mounted the transmitter "curtain" arrays, and subsequently for the West Coast and other chains both masts and array.


The final number of CH stations totaled 58. This is a link to a description of the different types.


Just as a matter of interest the facility of the CH system was actually turned against the UK by the Germans using the bistatic radar principle in their Klein Heidelberg system, now back in fashion in OTH radars.  










Pulse Width













PRF Variable around 400.  When on 200’ tower or on 200’ cliffs, range on target at 500’ is 110 miles. Aerial is a 5 bay, 4 stack of dipoles . Horizontal angle of beam about 20 Deg.







Types 1 & 2 in close proximity operating as one unit.



















Type 2 Tower and gantry mounts          Type 2 Transmitter station                                             Type 2 Receiver station with PPI and plotting board


Early CHL stations operated similar to their larger Chain Home counterparts, measuring the range and angle to the target. These were later upgraded with plan-position indicator displays (PPI) which provide a map-like 2-dimensional view of the airspace around the station. This eliminated the need to translate range and bearing measures into positions, instead the operators could simply plot the "blips" directly on a paper map, both for record keeping as well as determining the grid locations of the targets.



CHL Description


CHEL Description


Type 2 and Type 52 - 56


There are excellent descriptions of CH and CHL equipment in the book "RADAR How it all Began" by Jim Brown published by Janus in 1996. It is the story of Metro Vick's production of the Chain Home transmitter, the special tetrode valve designed by Dr. Dodds and subsequent work on other radars.


The final number of all radar installations totaled 230.


Naval Operations

1940/1  The Company was involved in the fitting of RDF for early warning against air attack to Navy capital ships. Modified Air-to-Surface metric equipment fitted to smaller ships. A crash programme to develop a small set also capable of detecting surfaced submarines was delivered in 1941. An improved form of aircraft warning system was the Type 281. 


Type 281

Type Aerial outfit Peak power (kW) Frequency (MHz) Wavelength (mm) In service
281 AQB 350 85 3,500 1940


Metric air warning set with separate Tx / Rx antennas. Type 281B had combined Tx / Rx antenna. First fitted to HMS Dido then HMS Prince of Wales[2] This set also had a secondary surface search and gunnery capability and used a Precision Ranging Panel. The Type 281 ranging system allowed the user to select either a 2000yd to 14000yd or a 2000yd to 25000yd range display with range accuracies of 50 or 75yds RMS, respectively.


Army Operations

There were parallel developments in this branch of he Armed Sevices - see here and here


Ground Controlled Interception

There is an excellent description of the mechanics of this mode of operation given in the second chapter of "Radar and Radar Techniques" by Denis Taylor


Type 8 

There were various marks of this radar, mobile and semi-static, replaced by the Type 7. 


This is the early war-time Type 8 for Ground Controlled Interception (GCI). Two outfits like

this were needed as the automatic Transmit / Receive switch had not been invented hence one aerial could not serve both Tx and RX. They could be swept from side-to-side but not rotate. Inside a man pedaled to achieve this. The two had always to be on the same bearing so that was a bit problematic.


Radars Type 7 and 8 at RAF Sopley













Another variation of a GCI radar using CHL arrays as described on page 26 of Taylor's book














Type 7





Power (Peak Pulse Width










3,5 or  8uS



Final static GCI radar known as Happidrome. Effective Range 90 miles. Aerial 30’ x 25’ comprising three separate aerials at 7.5’, 12.5’, & 25’.Can combine these or use separate. Rotates at up to 8 RPM. Can detect a target at 1000’ at 30 Miles. Transmitter is a CHL type. Height finding between 2.5 and 20 Deg.




Type 7 on The Web:


Radar Type 7 in detail.

Radar Type 7 at RAF Holmpton

Radar Type 7 but focuses mainly on the ROTOR program

Early air defence radar



Type 9

Mobile Chain Home Radar deployed in the field. The aerials were supported on the two 105-ft collapsible towers. Used as gap filler, and before main stations were built. Also used as buried reserve at CH stations, also used overseas. Later versions had four lines of shoot.



Type 11






Pulse Width









goes to MK8






Mk1 was mobile. Output Device is NT99. Mobile sets as standby if the 200MHz band was jammed. 600MHz was used by Germany.. Later versions from Mk5 Were coherent. First versions had rotary spark gap modulator. Horizontal beam 4 Deg, Vertical 11 Deg.





Magnetron Development

1940/1  The Vacuum Laboratories at Baddow take over magnetron development and production.


1942  Following improvements to the magnetron the Chelmsford factory produced amplifier units for a new naval radar Type 271 which went on to become the initial radars used for CHEL operation. The Admiralty continued development of the Type 271 radar and the improved model, known as the Type 277 entered R.A.F service as the Type 14.


Centimetric radar

This link is to a paper written by Mike Scanlan first published in the GEC Review


Type 13





Power (Peak) Pulse Width










goes to Mk5 with new aerial

Height Finder



0.6 or 1.9uS



Only  13 made. Used twin parabolic dishes. Based on 277. Also known as CMH.  Nodding Height finder. First versions were not very successful and were initially used for low angle detection fixed at 2.5 degrees. Aerial was twin parabolic cheese 20’ x 18”. Beam widths 1.75 x 6.5 Deg. Could nod between -1 and +20 Deg. Range 60 miles, at which it was accurate to 500’.






A number of Type 13 radars were manufactured by Scanners Limited in Gateshead. Many passed through MWT at Rivenhall in both static and mobile versions. The mobile versions were mounted on hydraulic jacks and could be raised and lowered onto a  heavy vehicle chassis. The transmitter/receiver and turning gear were mounted in a cabin behind the waveguide fed antenna and the whole assembly rotated as a single unit.


In most cases the mobile Type 13's formed part of a radar convoy comprising a search radar (usually a Type 14); an operations vehicle containing the display and communications facility and one or two diesel generator vehicles. These systems were assembled and tested at Rivenhall prior to shipment to a customer. The writer recalls that a number of "convoys" were supplied to India and Pakistan in the late 50's and early sixties. This combination was termed a Type 21.


In 1950 static Type 13 and 14 radars were installed at London Heathrow airport and were the forerunner of ATC surveillance radars in the UK.

















Static Type 13 and S264 (Believed to be at Heathrow)                            Mobile Type 13 (later aerial and earlier aerial)

(Picture: R. A. Webb)


Type 14





Power (Peak) Pulse Width








goes to MK9 ( with new aerial



0.6 or 1.9uS



Based on 277. Became Type 51. Mk1 -5 had cheese aerial, 20’ x 3’  From 400’ cliff will spot all targets  above 0.01 Deg elevation.





Mobile type 14 (earlier and later aerials)


Type 15 - successor to Type 8



Type 16 - fighter direction 


Operation Overlord - D-Day June 1944 


 For D-Day Marconi designed, developed and manufactured from research carried out by TRE an airborne system, code named Bagful, TR3549, comprising R1624 and T1360, a self-recording L-band equipment for the interception of signals from the Wurzburg radar, recording the wavelength, time and duration of the received signal and approximate positions of enemy radar stations which was in large-scale operation prior to the invasion to build up a dossier. On June 6th a multiplicity of jamming stations, in an operation code named Carpet paralysed the Germans radar networks. One such example is here.


Also for the invasion Marconi Marine provided servicing for all radio, echo sounding and radar equipments.


This (very large file) is a document covering all electronic systems used for communications, detection and navigation systems during the invasion. The following links describe radar equipment which featured in addition to the mobile units already described. The adventures of one such unit are described by "Gerry" Taylor in Colin Latham's book "Radar: A Wartime Miracle".



A rather quaint overview of wartime radar published in Flight magazine in June 1945





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