THORN EMI ELECTRONICS (TEE) RADAR DIVISION Airborne Early Warning (AEW) systems were initially used to protect naval forces from air attack, later systems have been designed to provide surveillance on a grand scale and are consequently very expensive and require large aircraft to accommodate them. This paper presents an argument for a more modest radar system which nevertheless meets the key AEW operational requirements and provides adequate warning of the approach of high speed aircraft. Experience gained from a long line of airborne radars has established design criteria for a software control, multi-role radar system with advanced electronic counter counter measures. Modern signal processing has allowed size and weight to be reduced so that this high performance radar may be carried by a wide variety of relatively small aircraft. The radar's primary role is AEW and facilities are incorporated for the automatic detection and tracking of airborne targets flying at all heights, including very low level, against any background.