Freya radar

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A 1941 RAF PRU photograph of the two Freyas at Auderville

Freya was an early warning radar deployed by Germany during World War II, named after the Norse Goddess Freyja. During the war over a thousand stations were built. A naval version operating on a slightly different wavelength was also developed as Seetakt. Freya was often used in concert with the primary German gun laying radar, Würzburg Reise ("Large Wurzburg"), finding targets at long distances and then "handing them off" to the shorter-ranged Würzburgs for tracking.

First tests of what would become the "Freya" were conducted in early 1937, with initial delivery of an operational radar to the Kriegsmarine in 1938. The Freya radar was in fact much more sophisticated than its British counterpart, Chain Home (CH), and by operating in the 1.2 m wavelength (as opposed to ten times that for the CH) the Freya was able to use smaller antennas and also offer better resolution. Unfortunately for the German war machine, 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. It also appears that radar was simply not considered as important by the Germans^{[citation needed]}, whereas in England the development and deployment of Chain Home was considered to be of the utmost importance.

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 semi-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 fictionalized 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'.