Freya radar 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 . Development . 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 . Apparently , Germany paid a lot more attention to radar development at this time than Great Britain later in the war . The Freya radar was already more advanced than its British counterpart , Chain Home . It operated on a wavelength ( 250 MHz ) while Chain Home used 12 m . This made for a drastically higher resolution of the German system , which therefore was able to detect much smaller objects . 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 , could be installed a lot quicker , which meant that the complete Chain Home network was in place in time for the Battle of Britain . Freya supported an early version of IFF . Aircraft equipped with the FuG 25a " Erstling " 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 conical scanning . In that mode , a skilled operator could achieve an angular resolution of 0 . 1° . Deployment and operation . 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 . Later in the war , Freya operated in the band from ( 120 to 130 MHz ) , with a pulse width of 3 microsecond s , a peak power output of 15 to 20 $ 4 , and a pulse repetition frequency of 500 Hz . It had a maximum range of only , making it inferior to Chain Home , nor could it accurately determine altitude , but it was a fully steerable and semi - mobile system . Freya was first successfully used on December 18 , 1939 when two stations detected an approaching daytime raid by 24 RAF Vickers Wellington bombers at a range of 113 km and guided fighter planes toward them via radio . Only half of the Wellingtons returned to Britain undamaged . This performance left the Luftwaffe so impressed that already by the Spring of 1940 , eleven Freya stations were installed to guard Germany ' s western border . After the invasion of France in 1940 , additional Freya stations were built along the Atlantic coast . When Britain started its bombing raids , Hermann Göring ordered colonel ( later General ) Josef Kammhuber to install an efficient air defense . This led to the so - called Kammhuber Line into which then more Freya stations were integrated . In the later course of the war , Freya devices turned out to be vulnerable against chaff , which meant they could still be used for early warning but no longer for guiding fighter planes . British intelligence . One of the first to give British intelligence any details 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 Follett ' s novel " Hornet Flight " . Sneum ' s deed is also mentioned in R . V . Jones ' s " Most Secret War " as a ' most gallant exploit ' . Countermeasures . To counter Freya , the British used equipment called " Moonshine " . Carried by Boulton Paul Defiant s of the Special Duties Flight ( later 515 Squadron ) , a single set retransmitted a portion of the Freya signal amplifying the apparent return . Eight aircraft with Moonshine could mimic a force of 100 bombers . A second countermeasures system , " Mandrel " was a noise jammer which overwhelmed the signals from " Freya " . Individual aircraft were sent to orbit fixed positions off the enemy coast . By using nine aircraft , a gap could be knocked into the German ' s radar coverage , while further jammers were carried in the bomber stream to counter the inland Freya network .