Yomiuri Shimbun. Fair use may apply.
|Pulse Width||10 microsecond|
|Pulse Repetition Frequency
|Range||60 nautical miles (100 km) aircraft group
40 nautical miles (70 km) single aircraft
12 nautical miles (20 km) battleship
||Mattress: two horizontal sets of
four dipoles (transmitter) and two horizontal sets of three dipoles
|Resolution||2200 yards/20 degrees
2000 meters/20 degrees
|Production:||Sources disagree on the number of installations, but it appears that Type 21 was first fitted to Ise in 1942-4, Shokaku in 1942-8, Taiyo, Chuyo and Unyo in 1943-1, and others prior to 1943-8, with at least 30-40 sets deployed operationally.|
The Japanese Type 21 radar (also known as Mark 2 Model 1 Type 2) was installed on surface ships beginning in August 1943 and was nicknamed the Ship Mattress. Though nominally an air search radar, it was used for surface search also. Some officers at the Bureau of Naval Construction went so far as to recommend that production of all other types be canceled. A land-based version also existed, known as the Type 1 Model 2, which was known to the Japanese as the Mobile Mattress. Examples of the latter were captured at Roi-Namur and Kwajalein.
The first prototype was installed on Ise
just prior to the battle of Midway.
The radar was subsequently installed on carriers, battleships, and cruisers. As with other Japanese
radars, reliability was shaky, with failure of one of its 54 vacuum
tubes all too frequent. Taiho went to the Battle of the
Philippine Sea with one of
its two Type 21 radar sets barely operational.
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