The AN/APG-77 is a multifunction low probability of intercept radar installed on the F-22 Raptor fighter aircraft. The radar was designed and initially built by Westinghouse and Texas Instruments, and production continued with their respective successors Northrop Grumman and Raytheon after acquisition.
It is a solid-state, active electronically scanned array (AESA) radar. Composed of 1956 transmit/receive modules, each about the size of a gum stick, it can perform a near-instantaneous beam steering (in the order of tens of nanoseconds).
The APG-77 provides 120° field of view in azimuth and elevation,. APG-77 has an operating range of while unconfirmed sources suggest an operating range of , against a target. A range of 400 km or more, with the APG-77v1 with newer GaAs modules is believed to be possible while using more narrow beams.
More than 100 APG-77 AESA radars have been produced to date by Northrop Grumman, and much of the technology developed for the APG-77 is being used in the APG-81 radar for the F-35 Lightning II. The AN/APG-77 system itself exhibits a very low radar cross-section, supporting the F-22's stealthy design.
The APG-77v1 was installed on F-22 Raptors from Lot 5 and on. This provided full air-to-ground functionality (high-resolution synthetic aperture radar mapping, ground moving target indication and track (GMTI/GMTT), automatic cueing and recognition, combat identification, and many other advanced features).