SCIENCE

RADAR AND ITS DEVELOPMENT IN EUROPE (1930 - 1944)

Introduced by R. Simmonds on 26 March 1999

"The outcome of war is not decided by brave men on either side, but by the side making the least mistakes" ( Field Marshall Montgomery)

The speaker showed how this quotation applied to the development of radar in Europe, with a critical effect on the outcome of the Second World War.

During and after the First World War the sound of the engine was the first indication of an aircraft. As the speed of aircraft increased this provided insufficient warning to `scramble' fighters to combat approaching bombers. In 1932, Baldwin said "the bombers will always get through", and set up a committee.

In 1934 an assistant, "Skip" Wilkins, of Robert Watson-Watt at the Radio Department of the National Physical Laboratory, noticed that radio programmes suffered a disturbance when an aircraft flew near a transmitter. Trials followed using the BBC transmitters at Daventry and by 1939 a chain of radar stations had been built all down the East coast of the UK, which could detect an aircraft 75 miles away. They used horizontal polarisation to match the wing-span of approaching aircraft.

In Germany, in 1933 the Navy's Signals Research Division was developing a sonic device, but it was decided to develop a radio-detection system. After attempting to interest Telefunken unsuccessfully, the head of SRD, Dr Künold set up his own firm, GEMA. By March 1934 they had an apparatus for test, which achieved a range of 12 km in obtaining an echo from a ship and 700m from an aircraft which passed overhead during the trial. It was found that a long wavelength gave better results and a decision was made to use 2m. with vertical polarisation, which had been found suitable for detecting ships at sea (the first mistake).

In 1938 the Luftwaffe became interested and ordered equipment from Telefunken.

The political decisions, taken in September 1939, to curtail any development unless it could produce results in a few months, based on the belief that it would be a short war, slowed development of new methods, particularly microwave technology (the second mistake). In addition the Jews were removed from the laboratories, so some of the best brains were lost (the third mistake).

In November 1939, RV Jones was presented with the Oslo Report, details of a dozen German weapons or developments, provided by an anti-Nazi German physicist. It included a description of a 50 cm. radar system and a pulsed radar which had detected British planes at 75 km. RV Jones organised counter-measures to such devices and further developments, such as H2S airborne radar, based on the cavity magnetron, which were critical in winning the war at sea as well as in the air.

R. Simmonds