AN/APG-81
The AN/APG-81 is an active electronically scanned array fire-control radar designed by Northrop Grumman Electronic Systems for Lockheed Martin’s F-35 Lightning II.
The APG-81 is a successor radar to the F-22 Raptor’s AN/APG-77, and has an antenna composed of 1,676 transceivers. Over three thousand APG-81 AESA systems are expected to be ordered for the F-35, with production to run beyond 2035, including large quantities of international orders.
The APG-81 enhances the F-35's multirole mission requirement operating as an electronic warfare aperture utilizing the AESA's multifunction array. Using electronic protection, electronic attack and electronic support measures, it enables the F-35’s capability to suppress and destroy advanced enemy air defenses.
This Joint Strike Fighter AESA radar is a result of the US government's competition for the world's largest AESA acquisition contract. Westinghouse Electronic Systems and Hughes Aircraft received contracts for the development of the Multifunction Integrated RF System/Multi-Function Array in February 1996. Lockheed Martin and Northrop Grumman were selected as the winners of the Joint Strike Fighter competition; the System Development and Demonstration contract was announced on 26 October 2001.
Capabilities of the AN/APG-81 include the AN/APG-77's air-to-air modes, plus advanced air-to-ground modes, including synthetic aperture radar high resolution mapping, multiple ground moving target indication and track, combat identification, electronic warfare, and ultra high bandwidth communications. The F-22 radar from Lot 5 aircraft onward is the APG-771 drawing heavily on APG-81 hardware and software for its upgraded air-to-ground capabilities.
In August 2005, the APG-81 radar was flown for the first time aboard Northrop Grumman's BAC 1-11 test aircraft. The radar system accumulated over 300 flight hours by 2010. The first test flight on Lockheed Martin's CATBird avionics test-bed occurred in November 2008.
In June 2009, the F-35’s APG-81 radar was integrated in the large-scale military Exercise Northern Edge 2009 mounted on the front of a Northrop Grumman test aircraft. The test events "validated years of laboratory testing versus a wide array of threat systems, showcasing the extremely robust electronic warfare capabilities of the world's most advanced fighter fire-control radar."
Announced on 22 June 2010, the radar met and exceeded its performance objectives successfully tracking long-range targets as part of the first mission systems test flights of the F-35 Lightning II BF-4 aircraft.
The AN/APG-81 team won the Department of Defense 2010 David Packard Excellence in Acquisition Award for performance against jammers.
In January 2023, it was reported that the AN/APG-81 would be replaced by a new radar, the AN/APG-85 on Block 4 F-35s. The APG-85 had been mentioned in a budgetary document in December 2022.
In accordance with the Joint Electronics Type Designation System, the "AN/APG-81" designation represents the 81st design of an Army-Navy airborne electronic device for radar fire-control equipment. The JETDS system also now is used to name all Department of Defense and some NATO electronic systems.