Chain Home

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RAF base Poling ( West Sussex ) in 1945: the bunkered transmitter house on the left in front of the transmitter towers, on the right receiving antennas with the associated building

Chain Home (CH; German: home-chain ) was the code name of a system of radar stations that the British Air Ministry ( Air Ministry ) before and during the Second World War on the coasts of Britain were built to provide early warning of hostile aircraft.

The entire chain Home radar chain was initially made up of two types of devices: the AMES Type 1 ( A ir M inistry E xperimental S tation ; German: Experimental Station of the Ministry of Aviation type 1) with a wavelength (of 10 to 13.5 meters frequency 30-22 MHz) in the ten meter band, which were responsible for the early warning of soaring aircraft up to 200 km away, and the Chain Home Low (CHL) / AMES Type 2 , which operates at 200 MHz on a wavelength of 1.5 meters in the ultra-short wave range , which has a lower range had km of around 80, but up to 150 meters, even low-flying machines altitude above ground could capture. At the beginning of 1943, the Chain Home Extra Low (CHEL; AMES Type 13 or 14) was used, which worked in the decimeter wave range with frequencies around 3 GHz (10 cm wavelength).

overview

Radar range 1939-1940
The chain home mast in Great Baddow

From May to August 1939, the German airship LZ130 undertook two flights along the British coastline to investigate whether the towers built from Portsmouth to Scapa Flow were used for radio location of aircraft. A range of tests were performed from the LZ130, from receiving radio waves, analyzing magnetic fields and radio frequencies, to taking photos. Despite extensive equipment with measuring devices, no emissions associated with radio location could be detected, as the wrong frequency range above 200 MHz (decimeter wave) was observed, which was not used by the British at the time. The result of the two reconnaissance flights was that the tall towers on the coast did not belong to a radar network, but a radio network of the Royal Navy or to support rescue operations.

The chain home stations were set up along the coast, first on the English Channel in the south and in the east on the North Sea coast of England, but later on the entire British coast including the Shetland Islands . The first stress test was the Battle of Britain ( Battle of Britain ) in 1940, when approaching bomber of the German Luftwaffe could be detected early enough.

The chain-home system was designed to be very simple, and to ensure combat readiness it was rushed into operation by the Aviation Department's Bawdsey Research Station, under the direction of Robert Watson-Watt . The pragmatist Watson-Watt believed that the third-best but available solution was preferable to an unavailable second-best and a never-available best solution. Chain Home was certainly the third best system, suffering from outages and false positives, but it was the best system available and it provided much-needed information.

During the fighting, the chain home stations - especially in Ventnor on the Isle of Wight  - were attacked several times between August 12 and 18, 1940. At one point, the Kent radar area, including the Dover station, was inoperable due to a hit on the power supply. The wooden houses with the radar equipment were damaged, but the towers remained functional thanks to their steel framework construction. Since the towers remained undamaged and the signal connection could soon be restored, the Luftwaffe leadership assumed that it would be difficult to destroy the stations with bombs and left them undisturbed for the rest of the war. The German air force command was either not aware of the importance of the “Chain Home” radar stations for British air defense, or was deceived by the behavior of the British, because increased attempts to (dis) failed to the last.

The chain home system was dismantled after the war, only a few steel lattice masts remain and have been put to a new use in the 21st century. One of these 110 m high transmitter masts is now on the BAE Systems factory premises in Great Baddow , Essex . This mast originally comes from Canewdon and is probably the last one that has been preserved unchanged.

Chain Home used separate transmitting and receiving antennas. The transmitting antennas were supported by 110 meter high free-standing steel lattice towers, while the receiving antennas were supported by 73.15 meter high wooden towers.

The chain home system is comparable to the German Freya radar.

Technical specifications

  • Frequency : 20-30 MHz
  • Wavelength : 15-10 m
  • Impulse power : 350 kW (later 750 kW)
  • Pulse repetition frequency : 25 Hz and 12.5 Hz
  • Pulse duration: 20 microseconds
  • Range: 200 km
  • Search sector: 120 degrees, not pivotable
  • Number of stations: 18 (time-synchronized from the power supply network to avoid interference)

Chain Home / Ames Type 1 locations


literature

  • Michael Bragg: RDF1 The Location of Aircraft by Radio Methods 1935-1945. Hawkhead Publishing, Paisley 1988, ISBN 0-9531544-0-8 , The History of Aerial Surveillance Radar in Britain during World War II. (English).
  • Colin Latham, Anne Stobbs: Radar A Wartime Miracle. Sutton Publishing Ltd, Stroud 1996, ISBN 0-7509-1643-5 , History of Radar in Great Britain during World War II, Telling the Men and Women Who Were There .
  • David Zimmerman: Britain's Shield Radar and the Defeat of the Luftwaffe. Sutton Publishing Ltd, Stroud 2001, ISBN 0-7509-1799-7 (English).
  • Louis Brown: A Radar History of World War II. Institute of Physics Publishing, Bristol 1999, ISBN 0-7503-0659-9 (English).
  • EG Bowen: Radar Days. Institute of Physics Publishing, Bristol 1987, ISBN 0-7503-0586-X (English).

Web links

Individual evidence

  1. ↑ Presentation of the history of radar (PDF; 4.8 MB)
  2. ↑ geschichtsspuren.de (formerly lostplaces.de): The development of radio measurement technology, Markus Scholz, June 14, 2005