Monica (radar)
Monica was a radar- based warning device introduced in the spring of 1942 for British night bombers of the Royal Air Force (RAF). Using tones of different frequencies in the intercom , it informed the rear gunner that something was approaching. Its frequency of use was around 300 megahertz .
To the regret of the British, the Germans were able to quickly develop the passive radar receiver FuG 227 Flensburg , which was used by the Luftwaffe from spring 1944 . Now bombers with active Monica could be targeted and tracked. In 1944, a Flensburg- equipped night fighter Ju 88 G -1, identification 4R + UR, accidentally landed on RAF Woodbridge airfield . During the investigation, the effectiveness of Flensburg was recognized and Monica was immediately removed from all British bombers.