Clandestine radar studies in France under the German occupation (1940–1942)

In the pre-WWII years the French CSF company, relying on its magnetron researches, was the first to take a specific interest in centimetric radar. Its “obstacle detector” installed in 1935 on the liner Normandie is well known. Two military versions, a “naval telemeter” and an anti-aircraft radar, both on λ= 16 cm, were derived in 1939. When the dramatic irruption of German armies in Paris in June 1940 interrupted these promising developments, CSF managed to transfer just in time its magnetron achievements to its English partner GEC. But it is less known that, over the next two years, it also carried on with a clandestine development of its naval centimetric prototype. At the time, no equivalent was found in the Allied Navies, and it could be seen in the global radar story as the first centimetric gun guidance radar. All ended in November 1942 when Hitler gave his troops the order to capture the French fleet in the so-called “Free Zone” at Toulon. The CSF test model was destroyed before their arrival, together with the other operational radars that the French Navy had developed at this time. This was the end of French radar researches in the war period.