Radar, Airborne Interception, Mark IV, produced by USA as SCR-540, was the world's first operational air-to-air radar system. Early Mk. III units appeared in July 1940 on converted Bristol Blenheim light bombers, while the definitive Mk. IV reached widespread availability on the Bristol Beaufighter heavy fighter by early 1941. On the Beaufighter, the Mk. IV arguably played a role in ending the Blitz, the Luftwaffe's night bombing campaign of late 1940 and early 1941.
Group Captain "Paddy" Green achieved most of his 11 confirmed kills in this Mk. IV-equipped Beaufighter.
Bowen's first 6.7 m set broadcast from the Red Tower to the White Tower, both visible on the left side of this image of Bawdsey Manor.
The ungainly Heyford holds title to two important firsts in radar history; it was the first aircraft to be detected by radar, and the first to carry a radar system.
Avro Anson K8758, as seen from K6260. K6260 carried the radar unit while K8758 acted as a target.
Airborne Interception radar
Airborne Interception radar, or AI for short, is the British term for radar systems used to equip aircraft in air-to-air role. These radars are used primarily by Royal Air Force (RAF) and Fleet Air Arm night fighters and interceptors for locating and tracking other aircraft, although most AI radars could also be used in a number of secondary roles as well. The term was sometimes used generically for similar radars used in other countries.
The centimetric AI. Mk. VIII shown here on a Bristol Beaufighter set the pattern for AI radars well into the 1970s.
This Bristol Beaufighter Mk.VIF mounts the AI Mk. IV. The transmitter antenna is (just) visible on the nose, the left-side receiver just outboard of the landing lights.
This De Havilland Mosquito NF Mark XIII of No. 604 Squadron shows the distinctive upturned "Bull nose" containing the Mk. VIII radar
The Mk. X equipped Gloster Meteor NF.11
