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Description of the radar set, tactical-technical characteristics
frequency: X-band
pulse repetition time (PRT):
pulse repetition frequency (PRF):
pulsewidth (τ):
receiving time:
dead time:
peak power:
average power:
instrumented range: 300 NM (≙ 550 km)
range resolution:
hits per scan:
antenna rotation:


ASD was operating in the X-band navigation and bombing radar during the 2nd world war, developed between MIT Rad Lab, NRL, and Sperry. In 1943 became the ASD radar put into production. After the war, Philco took over production in 1946 and the radar got the designation AN/APS-3. ASD was the first effective American microwave search radar and was used by medium-sized patrol planes and by attack planes such as the US Navy’s Patrol Bomber Lockheed PV-1 Ventura, PV-2 Harpoon, and Grumman TBF Avenger. Ships could be detected up to 300 miles away, submarines at 15 miles, and other aircraft at 8 miles.

The availability of X-Band magnetrons reduced antennas and magnetron hardware by a factor of three in dimensions compared with the S-band. This permitted mounting transmitter-receiver-antenna elements of the radar in small under-wing pods, or in fairings built beneath the plane’s wing. The radar control and B-scope presentation with a diameter of 4½ inches were located in the fuselage. Forward search azimuth was 150 degrees wide, switching to 60 degrees for homing in on targets.


  1. Louis A. Gebhard, Evolution of Naval Radio-Electronics and Contributions of the Naval Research Laboratory, NRL Report 8300, 1979 (online preview)