H2S Radar




The H2S was the first airborne microwave radar using a cavity magnetron to generate previously unobtainable power levels, this cavity magnetron is the device inside every microwave oven today. The radar was designed to improve the accuracy of RAF bombing over Germany - it had been discovered that less than half the bombs dropped at night were falling within five miles of the target. The RAF has been criticised by historians for not developing the radio navigation beams like those used by the Luftwaffe to bomb British cities at night. This criticism ignores the fact that the German radio transmitters were based on the coast of France and the low countries and could cover much of the UK whereas the RAF would have to use UK based beacons. The world is not flat and curvature meant that the British beams would not be detectable over Germany at any altitude that a 1940 heavy bomber could operate at due to the much longer ranges. H2S allowed the attacking aircraft to map the ground it was flying over and find features such as towns, lakes and rivers. The images were very crude at first and improved steadily from its deployment in 1943. The remarkable picture below is a photo taken from the display of a US built H2S during the liberation of France, 6th June 1944. It shows of the Normandy beach head a few minutes before the British and Canadian landing craft reached the Juno and Gold beaches. The town of Caen is the bright spot at '7 O'Clock'.

(source : Radar, issue No.3, 30 June 1944, a US Army Publication).

The origin of the name H2S is uncertain, it was renamed as its original name was too suggestive of its function. The two theories for H2S are Hydrogen Sulphide (the rotten Egg smell) and 'Home Sweet Home'. The memoirs of the designers differ as to which is the correct origin.  



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