Chain Home / HEARTS TYPE 1 (Air Experimental Ministry Station = experimental Station of the Ministry for the Air) was code name for the coastal chain of stations Radar built by the Britanniques before and during the Second world war. The system included/understood two types of radars : the metric stations Chain Home , which provided alert radar to long range, and the stations Chain Home Low / HEARTS TYPE 2 centimetric, of shorter range, but which could detect the aircraft at low altitude.

The system Chain Home

From May to August 1939, the German Airship Zeppelin LZ130 made flights along the coast of Great Britain, in order to confirm the theory that the turns of 100m top built by the British of Portsmouth to Scapa Flow were used for the localization by radio of the planes. The LZ130 made a whole of tests, energy of the interception of radio transmissions to the catch of photographs, while passing by an analysis of magnetic and radio frequencies. However, the bad quality of the German equipment prevented them from detecting the British radars Chain Home, and mission LZ130 concluded from it that the British turns were not related to operations radar, but rather formed a network of naval radiocommunications and rescue.

The stations Chain Home were built along the British coast, at the beginning in the south and the east of the England, then on the whole of the coast, including the Shetland Islands. They were put to the test initially during the Bataille of England, in 1940 where they proved to be able to give advanced alarms of the raids of the Luftwaffe.

The system Chain Home was very primitive, and, to be ready with the combat, it was put in production in urgency by Sir Robert Watson-Watt at the research station of the Ministry for the Air of Bawdsey. This pragmatic engineer considered that the “third quality” goes, provided that the “second quality” cannot be produced in time, and that the “first quality” is never available. Chain Home was certainly of the “third quality” and suffered from noises and errors of detection. But it was nevertheless the best in the world at the time, and it provides critical information, without which the battle of England could have been lost.

Chain Home does not have anything the popular image of a radar. Contrary to the German radars, there are no revolving antennas sending a radioelectric beam of energy in “headlight”, while listening to the echoes. Chain Home has only fixed antennas. The network of emission emits a spread out “range”, covering a great angle, of a hundred degrees. The network of reception is composed of two antennas fixed at right angle one of the other. These antennas have a directional sensitivity, and according to the Azimut of the target, the echo is more or less strong in one that in the other. The operator must manually adjust a circuit of comparison as well as possible to consider the force relative of the two signals received. The vertical angle of the target is estimated by comparison with the force of the signals received in another whole of antennas located more close to the ground. The delay of the echo, of course, determines the distance.

During the battle, the stations of Chain Home, and particularly that of Ventnor on the island of Wight, were tackled many times between the 12 and on August 18th, 1940. It arrived one day that a section of the chain in Kent, whose station of Dover, is put out of state by a stroke of luck damaging the electrical communication. But, although the huts of wood concealing the equipment radar are damaged, the turns survived thanks to their robust construction out of steel beams. As the turns remained intact and that the signals were quickly given on the way, Luftwaffe concluded that the stations were too difficult to damage by bombardment, and left them quiet for the remainder of the war. If Luftwaffe had carried out how much these radar tracking stations were essential with British air defense, it is probable that it would have put all its resources to destroy them.

The system Chain Home was destroyed after the war, but some of the large steel towers remain, reconverted for new uses for the 21e century.

One of these transmitting towers of 110m top (see photo at the head page) is with the factory BAE Systems of Great Baddow in Essex (2003). It was initially in Canewdo, and it is claimed that it is that the only tower of Chain Home still in its original form, without modification.

Comparison with the Radar German Freya

August 1st

The small parasite of Heidelberg

The Germans deploy a very simple system of radar, the “ Petit parasite of Heidelberg ”, which enables them to track the British planes, by using the signals of the British radars of Chain Home. The character “in range” of the emissions of Chain Home gets a pair of signals to them which enables them to locate the planes. The primary education signal is the direct signal coming from the transmitter of Chain Home towards the German receiver. The second signal, weaker, which is that is considered on the plane. The time between these two signals gives the difference between the direct way and the considered way. This difference geometrically gives an ellipse on which the plane is. The hearths of the ellipse are the antennas transmitting and receiving, whose positions are known by the Germans. A simple directional antenna seeking the direction of the echo makes it possible to give the point of the ellipse where the plane is. This system gives to the Germans a Radar of 400km of range, with 1 with 2km of precision in distance and a degree in azimuth.

List sites of Standard Chain Home/HEARTS 1

The interested reader will refer to, where it will find the references geographical and often histories of each of the 59 sites

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Note

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