<P> The first production sets (Lichtenstein B / C) became available in February 1942, but were not accepted into combat until September . The Nachtjäger (night fighter) pilots found to their dismay, that the 32 - element Matratze array was slowing their aircraft up by as much as 50 km / h . In May 1943, a B / C - equipped Ju 88R - 1 night fighter aircraft landed in Scotland, which still exists in the 21st century as a restored museum piece; it had been flown into Scotland by a trio of defecting Luftwaffe pilots . The British immediately recognized that they already had an excellent countermeasure in Window (the chaff used against the Würzburg); in a short time the B / C was greatly reduced in usefulness . </P> <P> When the chaff problem was realized, it was decided to make the wavelength variable, allowing the operator to tune away from chaff returns . In mid-1943, the greatly improved Lichtenstein SN - 2 was released, operating with a VHF band wavelength changeable between 3.7 and 4.1 m (81 to 73 MHz). The British took longer to find jamming for the SN - 2, but this was eventually accomplished after July 1944 . The much longer set of eight dipole elements for the full Hirschgeweih (stag's antlers) antenna array replaced the set of thirty - two elements of the Matratze array from the UHF - band B / C and C - 1 sets, but with the early SN - 2 sets having a deficient minimum range of about a half - kilometer, aircraft often needed to retain the earlier gear to make up for this; until the deficiency was addressed . This sometimes resulted in full sets of both Matratze and Hirschgeweih antennas festooning the noses of German night fighters, causing a disastrous problem with drag until first a "one - quarter" subset of the Matratze array was created for a centrally mounted installation on the nose, replacing the full four - set UHF array . Then, as the minimum range problem was worked out with the SN - 2 sets later in 1943, the earlier UHF - band B / C and C - 1 sets and their antennas could be removed entirely . As the planned replacement for the Lichtenstein series of sets, the government - developed Neptun radar, operating on yet a third set of different mid-VHF band frequencies (from 125 MHz to 187 MHz) to avoid Window interference, was placed in production by early 1944, and could use the same Hirschgweih antennas - with shorter dipoles fitted - as the SN - 2 sets had used . By the 1943 - 44 timeframe, the SN - 2 and Neptun radars could also use the experimental Morgenstern German AI VHF - band radar antenna, using twin 90 ° angled three - dipole pairs of Yagi antennas mounted to a single forward - projecting mast, making it possible to fair the array for drag reduction purposes within a conical, rubber - covered plywood radome on an aircraft's nose, with the extreme tips of the Morgenstern's antenna elements protruding from the radome's surface . At least one Ju 88G - 6 night fighter of the NJG 4 night fighter wing's staff flight used it late in the war for its Lichtenstein SN - 2 AI radar installation . </P> <P> Although Telefunken had not been previously involved with radars of any type for fighter aircraft, in 1944 they started the conversion of a Marbach 10 - cm set for this application . Downed American and British planes were scavenged for radar components; of special interest were the swiveling mechanisms used to scan the beam over the search area . An airborne set with a half - elliptical radome enclosed dish antenna, code - named FuG 240 Berlin was completed in January 1945, and about 40 sets were built and placed on night - fighter aircraft . A few sets, code named Berlin - S, were also built for shipboard surveillance . </P> <P> In the years prior to World War II, Japan had knowledgeable researchers in the technologies necessary for radar; they were especially advanced in magnetron development . However, a lack of appreciation of radar's potential and rivalry between army, navy and civilian research groups meant Japan's development was slow . It was not until November 1941, just days before the attack on Pearl Harbor, that Japan placed into service its first full radar system . In August 1942, U.S. marines captured one of these first systems, and, although crude even by the standards of early U.S. radars, the fact the Japanese had any radar capability came as a surprise . Japanese radar technology was 3 to 5 years behind that of America, Great Britain, and Germany throughout the war . </P>

How did the english use radar to defend themselves from german attacks