page_title: Robert Watson-Watt
section_title: Aircraft detection and location
hierarchical_section_title: Robert Watson-Watt / RADAR / Aircraft detection and location
caption_attribution_description: English: Memorial plaque at site of first successful RADAR experiments, 26-2-1935. Location: Lat 52.195982° Lon -1.050121° near Daventry, Northamptonshire.
context_page_description: Sir Robert Alexander Watson Watt, KCB, FRS, FRAeS was a British pioneer of radio direction finding and radar technology.
  Watt began his career in radio physics with a job at the Met Office, where he began looking for accurate ways to track thunderstorms using the radio signals given off by lightning. This led to the 1920s development of a system later known as huff-duff. Although well publicized at the time, the system's enormous military potential was not developed until the late 1930s. Huff-duff allowed operators to determine the location of an enemy radio in seconds and it became a major part of the network of systems that helped defeat the U-boat threat. It is estimated that huff-duff was used in about a quarter of all attacks on U-boats.
  In 1935 Watt was asked to comment on reports of a German death ray based on radio. Watt and his assistant Arnold Frederic Wilkins quickly determined it was not possible, but Wilkins suggested using radio signals to locate aircraft at long distances. This led to a February 1935 demonstration where signals from a BBC short-wave transmitter were bounced off a Handley Page Heyford aircraft.
context_section_description: On 12 February 1935, Watson-Watt sent the secret memo of the proposed system to the Air Ministry, Detection and location of aircraft by radio methods. Although not as exciting as a death-ray, the concept clearly had potential but the Air Ministry, before giving funding, asked for a demonstration proving that radio waves could be reflected by an aircraft. This was ready by 26 February and consisted of two receiving antennae located about 6 miles (9.7 km) away from one of the BBC's shortwave broadcast stations at Daventry. The two antennae were phased such that signals travelling directly from the station cancelled themselves out, but signals arriving from other angles were admitted, thereby deflecting the trace on a CRT indicator (passive radar). Such was the secrecy of this test that only three people witnessed it: Watson-Watt, his colleague Arnold Wilkins, and a single member of the committee, A. P. Rowe. The demonstration was a success; on several occasions a clear signal was seen from a Handley Page Heyford bomber being flown around the site. The Prime Minister, Stanley Baldwin, was kept quietly informed of radar's progress. On 2 April 1935, Watson-Watt received a patent on a radio device for detecting and locating an aircraft.
  In mid-May 1935, Wilkins left the Radio Research Station with a small party, including Edward George Bowen, to start further research at Orford Ness, an isolated peninsula on the Suffolk coast of the North Sea. By June they were detecting aircraft at a distance of 16 miles (26 km), which was enough for scientists and engineers to stop all work on competing sound-based detection systems. By the end of the year the range was up to 60 miles (97 km), at which point plans were made in December to set up five stations covering the approaches to London.
  One of these stations was to be located on the coast near Orford Ness, and Bawdsey Manor was selected to become the main centre for all radar research. In an effort to put a radar defence in place as quickly as possible, Watson-Watt and his team created devices using existing available components, rather than creating new components for the project, and the team did not take additional time to refine and improve the devices. So long as the prototype radars were in workable condition they were put into production. They soon conducted "full scale" tests of a fixed radar radio tower system that would soon be known as Chain Home, an early detection system that attempted to detect an incoming bomber by radio signals. The tests were a complete failure, with the fighter only seeing the bomber after it had passed its target. The problem was not the radar, but the flow of information from trackers from the Observer Corps to the fighters, which took many steps and was very slow. Henry Tizard with Patrick Blackett and Hugh Dowding immediately set to work on this problem, designing a 'command and control air defence reporting system' with several layers of reporting that were eventually sent to a single large room for mapping. Observers watching the maps would then tell the fighter groups what to do via direct communications.
  By 1937 the first three stations were ready, and the associated system was put to the test. The results were encouraging, and an immediate order by the government to commission an additional 17 stations was given, resulting in a chain of fixed radar towers along the east and south coast of England. By the start of the Second World War, 19 were ready to play a key part in the Battle of Britain, and by the end of the war over 50 had been built. The Germans were aware of the construction of Chain Home but were not sure of its purpose. They tested their theories with a flight of the Zeppelin LZ 130, but concluded the stations were a new long-range naval communications system.
  As early as 1936, it was realized that the Luftwaffe would turn to night bombing if the day campaign did not go well, and Watson-Watt had put another of the staff from the Radio Research Station, Edward Bowen, in charge of developing a radar that could be carried by a fighte
caption: Closeup of memorial plaque
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