Emerson Electric's AN/APQ-153 was an I band radar system developed for the Northrop F-5E fighter aircraft. Required to fit into the tight confines of the originally radar-less F-5, the system offered relatively simple air-to-air modes and a short detection range. The AN/APQ-157 was a similar system with dual displays and controls for the twin-seat F-5F trainer. Many of the F-5's still flying have been upgraded to the improved AN/APQ-159.