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Military Early Days

Page history last edited by Alan Hartley-Smith 2 weeks, 1 day ago

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WW2 Military Radar Systems 1938 to 1945

 

Introduction

This covers the original metric floodlight radars with separate transmit and receive systems, for which Marconi Wireless Telegraph Ltd. designed and produced the arrays, 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 R.A.F 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

 

Interesting story about radar deployment on D-Day

 

 

CH

  

AMES

Type

 

Function

Power (Peak)

Pulse Width

 

PRF

 

Freq

 

Notes

 1

CH

1Mw

5-45uS

12.5, 25, 50

22.7-29.7MHz

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

 

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.

 

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.

 

Details of current status of other surviving sites - Swingate (Dover) - Northam Devon - Stenigot and some other details

 

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, and for all stations Marconi provided the transmitter `curtain' arrays, and subsequently for the West Coast and other chains.

 

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.  

 

CHL and CHEL

 

AMES

Type

 

Function

Power

(Peak)

Pulse Width

 

PRF

 

Freq

 

Notes

2

CHL

150Kw

3

400

200MHz

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.

3

CH/CHL

 

 

 

 

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.

 

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

 

AMES Type

 

Function

Power (Peak Pulse Width

 

PRF

 

Freq

 

Notes

7

GCI

80-100Kw

3,5 or  8uS

300-540

192-209MHz

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.

 


 

Type 11

 

AMES TYPE

 

Function

Power

(Peak)
Pulse Width

 

PRF

 

Freq

 

Notes

11Mk1

 

goes to MK8

CHL/GCI

50Kw?

4

500

565MHz

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.

 

 

Description

 

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

 

AMES Type

 

Function

Power (Peak) Pulse Width

 

PRF

 

Freq

 

Notes

13Mk1

 

 

goes to Mk5 with new aerial

Height Finder

CMH Mk1

500Kw

0.6 or 1.9uS

500

3GHz

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’.

 

Description

 

Simulation

 

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

 

AMES Type

 

Function

Power (Peak) Pulse Width

 

PRF

 

Freq

 

Notes

14Mk1

goes to MK9 ( with new aerial

CHEL

500Kw

0.6 or 1.9uS

500

3GHz

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.

 

Description

 

 

Mobile type 14 (earlier and later aerials)

 

Type 15 - successor to Type 8

 


 

Type 16 - fighter direction 
 

 

1945  

 

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

 

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

 

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