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Description of the radar set, tactical-technical characteristics

Figure 1: CXAM

Figure 1: CXAM

frequency: 200 to 400 MHz
pulse repetition time (PRT):
pulse repetition frequency (PRF): 1 640 Hz
pulsewidth (τ): 3 µs
receiving time:
dead time:
peak power: 15 kW
average power:
instrumented range:
range resolution: ±275 m; ±3°
beamwidth: 14°
hits per scan:
antenna rotation: 5 rpm


The CXAM radar is the first serial production radar deployed on U.S. Navy ships. It was developed at the United States Naval Research Laboratory (NRL) by physicist Robert Morris Page and his team during the 1930s. The Radio Corporation of America (RCA) received the first order in 1939 and delivered the prototype in 1940.

The first radars were installed in September on the battleship USS California, the aircraft carrier USS Yorktown, and the heavy cruisers USS Pensacola, USS Northampton, USS Chester, and USS Chicago. The next fourteen were renamed CXAM-1 because they included some enhancements.

The entire radar had nine components and weighed about 2,300 kilograms, 680 of which were for the 4.6 m by 4.8 m wide antenna mounted on the ship’s mast. A duplexer was used to use the same antenna for transmitting and receiving. Echoes were observed on an A scope.

Source: US Naval History & Heritage Command, Shipborne Search Sets (www.history.navy.mil)

Picture gallery of CXAM

Figure 2: Antenna post of CXAM