Serrate was a World War II Allied radar detection and homing device that was used by night fighters to track Luftwaffe night fighters equipped with the earlier UHF-band BC and C-1 versions of the Lichtenstein radar. It allowed RAF night fighters to attack their German counterparts, disrupting their attempts to attack the RAF's bomber force.
The first Serrate systems were developed from the AI Mk. IV radar, which just happened to have antennas almost perfectly suited to receiving the Lichtenstein signals. Serrate simply disconnected the display from the radar's own transmitter and receiver and connected it to one tuned to the Lichtenstein. This produced a display indicating the direction to the German aircraft, but not the range. By carefully watching the movement of the target on the display the operator could estimate the range in general terms, near or far. When it appeared the target was close enough, the display was reconnected to the Mk. IV's own electronics to provide both ranging and directional information during the last moments of the attack.
Serrate operations began by No. 141 Squadron RAF on the night of 7 September 1943. 179 operational sorties yielded 14 claimed fighters shot down, for 3 losses. After that point, the Luftwaffe realized what was happening and quickly introduced new versions of their radars working on different frequencies. Unlike the earlier sets, which just happened to operate on frequencies very close to the British radars, the new sets required entirely new detectors, which took some time to develop. New versions of Serrate were introduced, and moved from the Bristol Beaufighter to the faster de Havilland Mosquito, but later operations were never as successful as the original ones.
Later intruder operations were often directed by the Perfectos device instead of Serrate. This worked by triggering the German IFF transceivers and receiving the reply on the same antennas as Serrate. As the timing of the request pulse was known, Perfectos revealed both the angle and range to the target, removing the need to switch to radar at the end of the approach.
The AI Mk. IV radar was the first operational aircraft interception (AI) radar. It was first used experimentally in April 1940, and entered widespread service in early 1941. These systems used a set of four receiver antennas that were arranged so they were most sensitive in different directions; two were sensitive above or below the aircraft, and the other two to the left and right. The output from these antennas was rapidly switched back and forth on the display, producing two blips for any given target, with the length of the blip indicating the strength of the signal in that direction. By comparing the length of the blips from, say, the upper and lower antennas, the operator could determine if the target was above or below their fighter.
For purely practical reasons, the antennas were shorter than ideal. A half-wave dipole for the system's 1.5 m wavelength signals should be about 75 cm, but antennas of this size produced considerable drag on the aircraft. As gain was not a limiting issue due to other limitations of the system, smaller antennas were adopted, about 30 cm long. By chance, the Germans selected a 50 cm wavelength for their own AI radars, which made the Mark IV antennas almost perfectly suited for receiving their signals. The suggestion was made early on that the system could be modified to display the signals from the German radars simply by connecting the antennas and display to a receiver tuned to the German frequencies.
By late 1941 a new generation of radars was appearing that were based on the new cavity magnetron instead of the traditional tube-based electronics of the Mk. IV. These operated at much shorter wavelengths, about 9 cm, thus requiring much smaller antennas while also providing much higher angular resolution. The production AI Mk. VIII radar version became widespread by late 1942 and were installed primarily on the de Havilland Mosquito, leaving the problem of what to do with the older Bristol Beaufighters mounting Mk. IV. This difficulty arose at the time that the use of the H2S radar was being debated within Bomber Command, with the concern being expressed that an aircraft lost over Europe would reveal the secret of the magnetron to the Germans.
At this point the idea of using the Mk. IV-equipped Beaufighters as intruder aircraft was once again raised. Lacking a magnetron, these presented no security risk, and offered a reasonable way to use these now obsolete night fighters. This was aided by the landing of a fully intact Junkers Ju 88R-1 night fighter in May 1943 in Scotland, by its defecting crew, revealing the latest operational frequencies of the German radars.
The technique described here is for the Monica tail warning radar: The technique developed was for the RAF night fighters to fly slowly off the bomber stream, mimicking the characteristics of a heavy bomber, until the rearward-facing Serrate (Monica) detector picked up the emissions from a Luftwaffe night fighter approaching. The Radar Operator would then pass directions to the pilot until the fighter was 6,000 feet behind, at which point the Beaufighter would execute a swift turn onto the tail of the German night fighter, pick up the enemy aircraft on his forward radar and attempt to down it.
Serrate was also subsequently fitted to de Havilland Mosquito night fighters.
No. 141 Squadron transferred to No. 100 Group Bomber Command in late 1943 and during the Battle of Berlin on the night of 16/17 December, a Mosquito crewed by Squadron Leader F. F. Lambert and Flying Officer K. Dear made Bomber Command's first successful Serrate-guided operational sortie when they damaged a Bf 110 with cannon fire. [1] The Serrate night fighter offensive preceded far greater and wide-ranging support operations by the specialist 100 Group during 1944-45.
A night fighter is a largely historical term for a fighter or interceptor aircraft adapted or designed for effective use at night, during periods of adverse meteorological conditions, or in otherwise poor visibility. Such designs were in direct contrast to day fighters: fighters and interceptors designed primarily for use during the day or during good weather. The concept of the night fighter was developed and experimented with during the First World War but would not see widespread use until WWII. The term would be supplanted by “all-weather fighter/interceptor” post-WWII, with advancements in various technologies permitting the use of such aircraft in virtually all conditions.
H2S was the first airborne, ground scanning radar system. It was developed for the Royal Air Force's Bomber Command during World War II to identify targets on the ground for night and all-weather bombing. This allowed attacks outside the range of the various radio navigation aids like Gee or Oboe, which were limited to about 350 kilometres (220 mi) of range from various base stations. It was also widely used as a general navigation system, allowing landmarks to be identified at long range.
The Naxos radar warning receiver was a World War II German countermeasure to S band microwave radar produced by a cavity magnetron. Introduced in September 1943, it replaced Metox, which was incapable of detecting centimetric radar. Two versions were widely used, the FuG 350 Naxos Z that allowed night fighters to home in on H2S radars carried by RAF Bomber Command aircraft, and the FuMB 7 Naxos U for U-boats, offering early warning of the approach of RAF Coastal Command patrol aircraft equipped with ASV Mark III radar. A later model, Naxos ZR, provided warning of the approach of RAF night fighters equipped with AI Mk. VIII radar.
The Lichtenstein radar was among the earliest airborne radars available to the Luftwaffe in World War II and the first one used exclusively for air interception. Developed by Telefunken, it was available in at least four major revisions, called FuG 202 Lichtenstein B/C, FuG 212 Lichtenstein C-1, FuG 220 Lichtenstein SN-2 and the very rarely used FuG 228 Lichtenstein SN-3.. The Lichtenstein series remained the only widely deployed airborne interception radar used by the Germans on their night fighters during the war — the competing FuG 216 through 218 Neptun mid-VHF band radar systems were meant as a potentially more versatile stop-gap system through 1944, until the microwave-based FuG 240 "Berlin" could be mass-produced; the Berlin system was still being tested when the war ended.
No. 100 Group was a special duties group within RAF Bomber Command. The group was formed on 11 November 1943 to consolidate the increasingly complex business of electronic warfare and countermeasures in one organisation. The group was responsible for the development, operational trial and use of electronic warfare and countermeasures equipment. It was based at RAF stations in East Anglia, chiefly Norfolk.
The Kammhuber Line was the name given by the Allies to the German night-fighter air-defence system established in western Europe in July 1940 by Colonel Josef Kammhuber. It consisted of a series of control sectors equipped with radars and searchlights and an associated night fighter. Each sector would direct the night fighter into visual range to target intruding bombers.
The Battle of Berlin was a bombing campaign against Berlin by RAF Bomber Command along with raids on other German cities to keep German defences dispersed. Air Chief Marshal Sir Arthur Harris, Air Officer Commanding-in-Chief (AOC-in-C) Bomber Command, believed that "We can wreck Berlin from end to end if the USAAF come in with us. It will cost us between 400 and 500 aircraft. It will cost Germany the war".
The Helmore/GEC Turbinlite was a 2,700 million candela (2.7 Gcd) searchlight fitted in the nose of a number of British Douglas Havoc night fighters during the early part of the Second World War and around the time of The Blitz. The Havoc was guided to enemy aircraft by ground radar and its own radar. The searchlight would then be used to illuminate attacking enemy bombers for defending fighters accompanying the Havoc to shoot down. In practice the Turbinlite was not a success, and the introduction of higher performance night fighters with their own radar meant they were withdrawn from service in early 1943.
Radar in World War II greatly influenced many important aspects of the conflict. This revolutionary new technology of radio-based detection and tracking was used by both the Allies and Axis powers in World War II, which had evolved independently in a number of nations during the mid 1930s. At the outbreak of war in September 1939, both the United Kingdom and Germany had functioning radar systems. In the UK, it was called RDF, Range and Direction Finding, while in Germany the name Funkmeß (radio-measuring) was used, with apparatuses called Funkmessgerät . By the time of the Battle of Britain in mid-1940, the Royal Air Force (RAF) had fully integrated RDF as part of the national air defence.
No. 255 Squadron RAF was a Royal Air Force Squadron formed as an anti-submarine unit in First World War and a night-fighter unit in the Second World War. The First World War squadron was formed from former Royal Naval Air Service coastal flights and was responsible for coastal anti-submarine patrols. It was disbanded after the war.
The FuG 240 "Berlin" was an airborne interception radar system operating at the "lowest end" of the SHF radio band, which the German Luftwaffe introduced at the very end of World War II. It was the first German radar to be based on the cavity magnetron, which eliminated the need for the large multiple dipole-based antenna arrays seen on earlier radars, thereby greatly increasing the performance of the night fighters. Introduced by Telefunken in April 1945, only about 25 units saw service.
Radar, Aircraft 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.
Radar, Airborne Interception, Mark VIII, or AI Mk. VIII for short, was the first operational microwave-frequency air-to-air radar. It was used by Royal Air Force night fighters from late 1941 until the end of World War II. The basic concept, using a moving parabolic antenna to search for targets and track them accurately, remained in use by most airborne radars well into the 1980s.
Aircraft interception radar, or AI radar for short, is a British term for radar systems used to equip aircraft with the means to find and track other flying aircraft. 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, notably the US.
A tail warning radar, sometimes TW for short, was a short-lived class of aircraft-mounted radar systems used to provide warning of another aircraft approaching from the rear.
Searchlight Control, SLC for short but nicknamed "Elsie", was a British Army VHF-band radar system that provided aiming guidance to an attached searchlight. By combining a searchlight with a radar, the radar did not have to be particularly accurate, it only had to be good enough to get the searchlight beam on the target. Once the target was lit, normal optical instruments could be used to guide the associated anti-aircraft artillery. This allowed the radar to be much smaller, simpler and less expensive than a system with enough accuracy to directly aim the guns, like the large and complex GL Mk. II radar. In 1943 the system was officially designated Radar, AA, No. 2, although this name is rarely used.
Radar, Air-to-Surface Vessel, or ASV radar for short, is a classification used by the Royal Air Force (RAF) to refer to a series of aircraft-mounted radar systems used to scan the surface of the ocean to locate ships and surfaced submarines. The first examples were developed just before the opening of World War II and they have remained a major instrument on patrol aircraft since that time. It is part of the wider surface search radar classification, which includes similar radars in ground and ship mountings.
Radar, Air-to-Surface Vessel, Mark III, or ASV Mk. III for short, was a surface search radar system used by RAF Coastal Command during World War II. It was a slightly modified version of the H2S radar used by RAF Bomber Command, with minor changes to the antenna to make it more useful for the anti-submarine role. It was Coastal Command's primary radar from the spring of 1943 until the end of the war. Several improved versions were introduced, notably the ASV Mark VI, which replaced most Mk. IIIs from 1944 and ASV Mark VII radar, which saw only limited use until the post-war era.
The SCR-720 was a World War II aircraft interception radar designed by the Radiation Laboratory (RadLab) at MIT in the United States. It was used by US Army Air Force night fighters as well as the Royal Air Force (RAF) in a slightly modified version known as Radar, Aircraft Interception, Mark X, or AI Mk. X for short.