Thames ARG: Chain Home and History of Radar – Report

Thames ARG LogoFriday the 1st of March 2013 saw an interesting look into the history of Radar in the UK, courtesy of Andy Tyler G1GKN.

The evening, hosted by the Thames Amateur Radio Group on Canvey Island, started at 7:30pm with members and non-members gathering for tea, cake and the opportunity to chat and mingle.

A video featuring an edited version of a video showing the recent Foundation training course was shown whilst the audience settled in for the main talk by Andy.

Accompanying Andy for his talk, was an impressive model of a Chain Home tower, pictured here, and before discussing the tower itself, the history and origin of Radar was discussed.

Chain Home Tower talk, with model
Chain Home Tower talk, with his model of the tower

The Origins of Radar

Andy told us that the first demonstration of a radar-like system was back in 1904. It was intended for use on ships, and had a detection range of just 3km. Following the 1912 Titanic disaster, calls were made for a detection system for icebergs. With the threat of World War I on the horizon, the Allied Submarine Detection Investigation Committee (ASDIC) was formed to find a technology to detect German U-boats.

Andy Tyler G1GKN, discussing the early days of UK RADAR
Andy Tyler G1GKN, discussing the early days of UK RADAR

The birth of Radar

1930s air defense in the UK was pretty primitive, relying mostly on acoustic mirrors, and in 1934, another committee, the Committee for the Scientific Study of Air Defense (CSSAC) was formed. After some discussion of the invention of a Death Ray, attention was turned to detection and in 1935, the Daventry Experiment was born. Robert Watson-Watt and Arnold Wilkins were able to detect a Heyford bomber successfully  from a range of around 8 miles, completing a successful test of what became Radar.

A short video followed, before discussion of secret experiments at Orfordness in Suffolk, where the detection range was extended to around 100km.

Chain Home Towers

Originally known by the designation AMES (Air Ministry Experimental Station) Type 1, each station had three 360 foot transmitter towers capable of an output power of 1MW. Wooden receiver towers were sited around half a mile way.

The system worked by pushing out a powerful pulse of RF. Any target ‘hit’ by the pulse would scatter the RF, and the returning signal could be used to plot contacts. Information on the height and direction of contacts was relayed to a plotter room and action could be taken.

By 1939, 21 Chain Home stations were operational.

The next development was IFF (Identification of Friend or Foe). The concept of an aircraft transponder for aircraft identification, first introduced in 1939, is still in use today.

World War II

Chain Home played a vital part in the Battle of Britain, and Andy pointed out that without Chain Home and RDF (Radio Direction Finding), we’d all probably be speaking German. As the war progressed, a more versatile system using microwave Radar came into action, but Chain Home was still used as a system to detect launch sites for V2 rockets.

Andy outlining the war years of the Chain Home Towers
Andy outlining the war years of the Chain Home Towers

Chain Home, post war

The system was effectively obsolete by 1945 and many of the towers were dismantled. Andy informed the audience that only five of the historic towers now remain: Dover, Great Bromley, Stenigot, Stock Holy Cross, and Great Baddow.

The Chain Home tower now at BAE in Great Baddow was originally one of the Canewdon towers, and was moved to be used for the Blue Streak ICBM project in 1956. Interestingly, Andy mentioned that the Canewdon site was used in the 1960s and 1970s by the UK Government to jam the pirate radio stations operating off the Essex coast.

In subsequent years, the Baddow tower has been used for a number of test projects by BAE systems, however the future of the Great Baddow Chain Home tower is uncertain. As the last complete tower in the UK, it would be a great shame if this important historical asset couldn’t be preserved. We owe a lot to the Chain Home Towers, and to the pioneering work of those behind Radar research.

Thanks very much to Andy for a fascinating talk on the history of Radar, a detailed description on the Chain Home technology, and for more on the historic landmark familiar to many Essex hams driving around Chelmsford.

As an aside, Pete M0PSX from Essex Ham was lucky enough to join Andy G1GKN and several other amateurs to work from the foot of the Gt Baddow Chain Home Tower as part of the 2012 commemoration of the Titanic disaster. For details of the day, see the following Essex Ham report: Chlemsford ARS working from Chain Home, Gt Baddow April 2012

Great Baddow Mast, used by GB100MWT
Working from the Gt Baddow Chain Home Tower in April 2012


Thames ARG Club Night

The club night held by the Thames Amateur Radio Group on Canvey attracted the largest attendance of a club night so far, and the raffle also proved popular, with prizes including a T-Shirt and a 2m/70cm handheld. Well done to Fred M6BZW for having the winning ticket and walking away with a handheld.

Fred M6BZW wins in Thames ARG raffle
Congrats to Fred Phillips M6BZW on winning a handheld radio in the Thames ARG raffle

A good night and a fascinating topic.

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