Freya radar

Freya

A 1941 RAF PRU photograph of the two Freyas at Auderville
Country of origin	Germany
Introduced	1939
Number built	1,000+
Type	Early warning radar
PRF	500 per second
Pulsewidth	2-3μs
Range	200 kilometres (120 mi)
Azimuth	360°
Power	20 kW

Freya was an early warning radar deployed by Germany during World War II; it was 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 the Seetakt.

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 by the GEMA company. Freya supported an early version of Identification friend or foe (IFF). Aircraft equipped with the FuG 25a "Erstling" IFF system could be successfully queried across ranges of over 100 km.

The "AN" version gained a switchable phasing line for the antenna. Switching in the phasing line led to a phase displacement of the antenna's radiation pattern and with that, a "squinting" to the left or right. This enabled the system in effect to switch from the rather broad "scanning for maxima" to narrow lobe switching. In that mode, a skilled operator could achieve an angular resolution of 0.1°.

The Freya radar was more advanced than its British counterpart, Chain Home. Freya operated on a 1.2 m (3.9 ft) wavelength (250 MHz) while Chain Home used 12 m. This allowed Freya to use a much smaller antenna system, one that was easier to rotate, move and position. It also offered higher resolution, allowing it to detect smaller targets. Because of its complex design, only eight Freya stations were operational when the war started, resulting in large gaps between the covered areas. The British Chain Home radar, although less advanced and more prone to errors, was simpler, which meant that the complete Chain Home network was in place in time for the Battle of Britain.

Freya was often used in concert with the primary German gun laying radar, Würzburg Riese ("Würzburg Giant"); the Freya finding targets at long distances and then "handing them off" to the shorter-ranged Würzburgs for tracking.