The AN APG-66 is a pulse-doppler radar designed specifically for the F-16 Fighting Falcon fighter aircraft. It was developed from Westinghouse's WX-200 radar and is designed for operation with the Sparrow and AMRAAM medium-range and the Sidewinder short- range missiles. APG-66 uses a slotted planar-array antenna located in the aircraft's nose and has four operating frequencies within the I J band.