Freya radar
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Freya radar was an early form of radar deployed by Germany during World War II, named after the Norse Goddess Freyja. During the war over a thousand stations were built.
First tests of what would become the "Freya" early warning radar were conducted in early 1937, with initial delivery of an operational radar to the Kriegsmarine in 1938. It appeared to receive a much lower priority than British radar until later in the war. The Freya radar was in fact much more sophisticated than the British Chain Home (CH) counterpart, and by operating in the 1.2 m wavelength (as opposed to ten times that for the CH) the Freya was able to be much smaller and yet offer better resolution. Unfortunately, due to the sophistication of the design, by the start of the war only eight of these units were in operation, offering sparse coverage. By comparison, the Chain Home radars, though primitive and prone to error, could be constructed much more rapidly, allowing the British to field a completed system in time for the Battle of Britain.
Later in the war Freya operated in the band from 2.5 to 2.3 meters / 120 to 130 MHz, with a pulse width of 3 microseconds, a peak power output of 15 to 20 kW, and a pulse repetition frequency of 500 Hz. However it had a maximum range of only 160 kilometers (100 miles) and could not accurately determine altitude, making it inferior to CH in those respects, but it was a fully steerable and a mobile system.
One of the first to give the British intelligence about the Freya Radar was a young Danish Flight Lieutenant Thomas Sneum, who, at great risk to his life, photographed radar installations on the Danish island of Fanø in 1941. He brought the negatives to England in a dramatic flight which is described in Ken Follet's novel Hornet Flight. Sneum's deed is also mentioned in R.V. Jones's Most Secret War as a 'most gallant exploit'.
