Naxos radar detector

The FuG 350 Naxos radar warning receiver was a World War II German countermeasure to SHF band centimetric wavelength radar produced by a cavity magnetron. It replaced Metox, which was incapable of detecting centimetric radar.

Telefunken built a simple detector named "Naxos" that could pick up 10 cm / 3 GHz H2S radar transmissions, and a more sophisticated detector named "Korfu" with greater range and accuracy.

Korfu saw little use, but Naxos saw widespread service. There were two different types of Naxos. "Naxos Z" was developed for night fighters and mounted in a teardrop-shaped blister on top of the fighter's canopy. It could detect an RAF bomber from much longer range than FuG 227 Flensburg. Another version, the S-band (2500-3700 MHz, 12–9 cm wavelength) FuMB7 Naxos U, was provided to U-boats to allow them to detect 10 cm / 3 GHz ASV (air to surface vessel) radar, though by that time the U-boats were entirely on the defensive and it did them only a little good. By one of those weird coincidences which occur in wartime, the U-Boats received their Naxos 10 cm detectors on the same day that RAF Coastal Command deployed its first 3 cm ASV radar sets. Naxos was further hobbled by the fact that it proved very fragile in field conditions, and working out the bugs ended up being a difficult task.

The "Naxos ZR" was fitted to the tails of German night fighters to warn them if they were being tracked by RAF De Havilland Mosquito night intruders fitted with the AI Mk.IV radar and its derivatives.

Naxos receivers were also combined with the parabolic antennas from Würzburg radar systems to produce a long-range receiver tuned to the British Oboe radio navigation system. The system later used a Domeyer receiver and became the Naxburg system. Oboe broadcast pulses from the aircraft that needed to be powerful enough to be received by ground stations in the UK. This made them relatively easy to pick out at short ranges, as long as the receiver was tuned to a suitable frequency. When such a signal was detected, false pulses identical to those received from the aircraft were re-broadcast from the ground. Stations in the UK thus received two or more signals for every signal they sent out, which confused the detectors.