Description of the radar set, tactical-technical characteristics
Figure 1: Type 285
|pulse repetition time (PRT):|
|pulse repetition frequency (PRF):|
|pulsewidth (τ):||1.7 µs|
|peak power:||25 kW|
|instrumented range:||8.5 NM (≙ 16 km)|
|hits per scan:|
Type 285 was operating in UHF-Band gunnery control radar for the British Royal Navy. It employed two types of aerials; one with 6 Yagi antennas and the other with 5 Yagis. In the six Yagi version, three antennas were used to transmit and three to receive. This arrangement produced a narrower 18 by 43 degree beam. Type 285P with five-element Yagi antennas used a duplexer with combined Tx/Rx function. The half-power beamwidth was reduced to 9.5 degrees along with a reduction in pulse width and higher transmitter power. The bearing measurement was accurate using lobe switching, but the tracking of aerial targets in elevation was very poor.
Type 285 was developed from the US American FD radar made by General Electric Company. The first prototype of the Type 285 radar was given in “Southdown”, a Hunt Class Destroyer in September 1940. The radar was also carried by some destroyers, although it was fitted to a different director. Later, it was replaced with the Type 275.