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Type 79

Description of the radar set, tactical-technical characteristics

Figure 1: Type 79Y in H.M.S. Curlew

Figure 1: Type 79 in H.M.S. Curlew

frequency: 43 MHz
pulse repetition time (PRT):
pulse repetition frequency (PRF): 50 Hz
pulsewidth (τ): 8 … 30 µs
receiving time:
dead time:
peak power: 70 kW
average power:
instrumented range: 40 NM (≙ 74 km)
range resolution:
hits per scan:
antenna rotation: (manually)

Type 79

Type 79 was operating in VHF-band experimental early warning radar in the Royal Navy.

Type 79 used separate antennas for transmission and receiving and an A scope to display the targets. Bearing was determined by rotating the aerials and setting them in the direction which gave maximum echo amplitude. But the beam width of the antenna pattern would theoretically be more than 200 degrees from a simple dipole with a reflector. A more accurate estimation of bearing was made by a procedure known as bracketing. Here the operator notes the bearings for zero signal on each side of the echo and calculate a mean of these two bearings.

Only three of these radar sets were fitted in the Navy by September 1939. One of them was fitted in H.M.S. Curlew, a cruiser specially adapted as an anti-aircraft ship. The experience gained with this radar was used in the development of the Type 279 radar.