Neptun (radar)

Neptun (Neptune) was the code name of a series of low-to-mid-VHF band airborne intercept radar devices developed by Germany in World 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]

Display device of FuG 218 Neptun

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.

Variants
Me 262 with AI radar FuG 218 Neptun

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]

  • Manufacturer: Flugfunkforschungsinstitut Oberpfaffenhofen (FFO, German for airborne radio research institut in Bavaria)
  • R1 version (backwards warning device)
  • Frequency: 182MHz
  • Power: 1.0kW
  • Transmitting and receiving antennas each consist of twin dipoles, mounted under and above the wings, respectively
  • Single display device with distance readout
  • Frequency: 125MHz
  • Power: 1.2kW
  • Range: 500 to 3,500m
  • Antennas in the form of spikes or (Fw 190) as "antlers" on right and left wings

FuG 217: Installed mainly in Ju 88 G-6, only a few Bf 110 G-4, He 219 or Me 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]

  • Manufacturer: FFO
  • R2 version (backward warning device)
  • J2 version (for single-engined night fighters)
  • Ausführung V/R (combined night fighter and backward warning device for two-engined fighters)
  • Two switchable frequencies: 158 and 187MHz
  • Search angle: 120°
  • Range: 440–4,370 yd (400–4,000 m)
  • Spike or "antler" antennas

FuG 218: mass-produced

  • Manufacturer: Siemens / FFO
  • R3 version (backward warning device)
  • J3 version (for single-engined night-fighters)
  • V/R version (combined night fighter and backward warning device for two-engined fighters)
  • Six switchable frequencies: 158 to 187MHz
  • Search angle: 120°
  • Range: 130–5,470 yd (120–5,000 m)
  • Weight: 110 lb (50 kg)
  • R3 and J3 with spike antennas and V/R with "antler" antennas.
  • G/R version (combined night fighter and backward warning device for two-engined fighters)
  • Only one single device built, replacing the 2kW transmitter with a 30kW transmitter. Range increased to up to 6.2 mi (10 km). This device was intended for the Dornier Do 335. "Antler" antennas.

See also

References
  1. Aders, p. 269
  2. "Focke Wulf 190 A6 R11 Nachtjäger". Archived from the original on 2009-12-27. Retrieved 2011-12-26.
  3. Aders, S. 210
  4. Aders, S. 268
  • (1) TME 11-219 Directory of German Radar Equipment
  • Gebhard Aders: Geschichte der Deutschen Nachtjagd, Motorbuch publishing corporation, 1977, ISBN 3-87943-509-X
  • File:Neptun FuG 217.pdf
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