Berlin can refer to several German 9 cm wavelength (3.3 GHz) microwave radars of World War II, developed after the capture of examples of the British cavity magnetron in the H2S radar. FuG 224 Berlin A of 1944, a PPI ground mapping radar FuG 240 Berlin N1 of 1945, an airborne interception radar for nightfighters FuMO 81, a naval development of the FuG 224 FuMO 83 Berlin I, for U-boats FuMO 84 Berlin II, for the type XXI U-boat