Neptun (Neptune) was the code name of a series of low-to-mid-VHF band airborne intercept radar devices developed by GermanyinWorld War II and used as active targeting devices in several types of aircraft. They were usually combined with a "backwards warning device", indicated by the addition of the letters "V/R" Vorwärts/Rückwärts, meaning Forward/Backward). Working in the metre range, Neptun was meant as a stop-gap until scheduled SHF-band devices became available (for instance the FuG 240/E cavity magnetron-based FuG 240 Berlin AI radar).[1]
Transceiving antennas used for Neptun on twin-engined night fighters usually used a Hirschgeweih (stag's antlers) eight-dipole array with shorter elements than the previous 90 MHz SN-2 radar had used or as an experimental fitment, the 90°-crossed twin-element set Yagi based Morgenstern single-mast-mounted array.
FuG 216: Experimental series to plan the further development. Installed in Fw 190 A-6/R11 and Bf 109 G-6[2] The aircraft were used by NJGr 10 until March 1944, after which some machines of 6./JG 300 (Kommando Plöger) were equipped.[3]
FuG 217: Installed mainly in Ju 88 G-6, only a few Bf 110 G-4, He 219orMe 262 received the Neptun. It could be combined with the additional Elfe device to automatically measure the target distance and fire the guns at a set range.[4]
FuG 218: mass-produced