page_title: Airborne Interception radar
section_title: Mk. X
hierarchical_section_title: Airborne Interception radar / Wartime systems / Mk. X
caption_attribution_description: English: Armstrong Whitworth Meteor NF.11, night fighter, in the Royal Military Museum at the Jubelpark, Brussels. Nederlands: Armstrong Whitworth Meteor NF.11, nachtjager, in het Koninklijk Legermuseum aan het Jubelpark te Brussel.
context_page_description: Airborne Interception radar, or AI for short, is the British term for radar systems used to equip aircraft in the air-to-air role. These radars are used primarily by Royal Air Force 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 term was first used circa 1936, when a group at the Bawdsey Manor research center began considering how to fit a radar system into an aircraft. This work led to the Airborne Interception Mk. IV, the first production air-to-air radar system. Mk. IV entered service in July 1940 and reached widespread availability on the Bristol Beaufighter by early 1941. The Mk. IV helped end the Blitz, the Luftwaffe's night bombing campaign of late 1940 and early 1941.
  Starting with the AI Mk. VII, AI moved to microwave frequencies using the cavity magnetron, greatly improving performance while reducing size and weight. This gave the UK an enormous lead over their counterparts in the Luftwaffe, an advantage that was to exist for the remainder of World War II.
context_section_description: The Mark X was the UK version of the SCR-720. This was originally promised for delivery in the summer of 1942, but ran into delays and only started arriving in December 1943. These were fit to the Mosquito to produce the NF.XVII and later versions. Conversions at operational units began in January 1944, and the Mk. X remained in service through the rest of the war.
  Compared to the Mk. VIII, the SCR-720 used a helical scan instead of spiral. The radar antenna was spun around a vertical axis through an entire 360 degrees 10 times a second, with the transmitter switching off when the antenna was pointed back towards the aircraft. This provided a 150 degree scan in front of the aircraft. As it spun, the antenna slowly nodded up and down to provide altitude coverage between +50 and -20 degrees. The resulting scanning pattern naturally produced a C-scope display on the CRT.
  In the post-war period the Mk. X became one of the UK's most widely used fighter radars, largely because a lack of foreign exchange to purchase newer designs, and the poor economy in general which required the RAF to have a "make do" attitude. The Mk. X would go on to equip the first jet-powered night fighters, including the Vampire NF.10 and Meteor NF.11. Small numbers remained in service as late as 1957.
caption: The Mk. X equipped Gloster Meteor NF.11
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