The AN/APG-81 is a solid-state active electronically scanned array radar, which was developed by Northrop Grumman Electronic Systems for the F-35 Lightning II fighter aircraft. The AN/APG-81 aims its beam by broadcasting radio energy which interferes constructively at certain angles in front of the antenna, which is fitted out with air and surface modes. The AN/APG-81 replaced the AN/APG-77 used in the F-22 Raptor aircraft. It improves on the older passive electronically scanned radars by spreading their broadcasts out across a band of frequencies, which makes it very difficult to detect over background noise. In August 2005, the APG-81 radar was flown for the first time aboard Northrop Grumman's BAC 1-11 airborne laboratory. Since then, the radar system has accumulated over 300 flight hours, maturing all five blocks of software.
More than 3,000 AN/APG-81 radars are expected to be ordered for the F-35, with production to run beyond 2035, and including large quantities of international orders. As of August 2007, 8 APG-81s have already been produced and delivered. The first three blocks of radar software have been developed, flight tested, and delivered ahead of schedule by the Northrop Grumman Corporation. Capabilities of the AN/APG-81 include the AN/APG-77's air-to-air modes plus advanced air-to-ground modes including high resolution mapping, multiple ground moving target detection and track, combat identification, electronic warfare, and ultra high bandwidth communications. The current F-22 production radar is the APG-77v1, which draws heavily on APG-81 hardware and software for its advanced air-to-ground capabilities.
AN/APG-81 Radar (Video)