The AN/APG-66 radar is an X-band[1] solid state medium range (up to 80 nautical miles (150 km; 92 mi)) pulse-Doppler planar array radar originally designed by the Westinghouse Electric Corporation (now Northrop Grumman) for use in early generations of the F-16 Fighting Falcon.

Subsequent upgrades have been installed in many varying aircraft types including the U.S. Customs and Border Protection's C-550 Cessna Citation, US Navy P-3 Orion, and Piper PA-42 Cheyenne II's.

Developed from Westinghouse's WX-200 concept radar, the AN/APG-66 was designed for operation with the AIM-7 Sparrow and AIM-9 Sidewinder missiles.

Air-to-ground offers ground mapping, doppler beam-sharpening, beacon, and sea modes.

In uplook mode, the radar uses a low Pulse-Repetition Frequency (PRF) for medium- and high-altitude target detection in low clutter, while downlook mode uses medium PRF for target detection in heavy clutter environments.