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Description of the radar set, tactical-technical characteristics

Figure 1: ASB

frequency: 515 MHz
pulse repetition time (PRT):
pulse repetition frequency (PRF):
pulsewidth (τ): 2 µs
receiving time:
dead time:
peak power: 200 kW
average power:
instrumented range: 50 mi (≙ 80 km)
range resolution:
hits per scan:
antenna rotation:


ASB was the first airborne radar used by U.S. forces during World War II. It was developed from a pulsed altimeter operating in the UHF band. as a targeting radar

Equipped with a duplexer, the radar used two Yagi antennas, each mounted under one of the wings. They were oriented slightly to the left and right such that their antenna patterns overlapped in the center. By quickly switching the radar from one of the antennas to the other, an angular bearing could be taken on an L-scope. The aircraft then had to be steered in the direction of the larger pulse.

Over 26,000 of this radar were produced from 1941 to 1944.