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SM Fighter Direction Radar


Photograph of SM radar console

U.S. Navy. Via ibiblio.org


Specifications:


Wavelength 10 cm
Pulse Width 1 microsecond
Pulse Repetition Frequency       775-825 Hz
Power 600-700 kW
Range 50 nautical miles (90 km) (bomber)
25 nautical miles (50 km) (battleship)
Scan rate 2-6 rotations per minute in search mode
7.5 scans per second over a 60 degree sector in track mode
Scope
PPI with 10, 50, and 80 nautical mile (19, 90, and 150 km) distance scales
Accuracy 200 yards/0.5 degree/500 feet
180 meters/0.5 degrees/150 meters
Resolution 200 yards/3 degrees
180 meters/3 degrees
Production First prototype installed on Lexington 3/43.
First two production models on Bunker Hill 9/43 and Enterprise 10/43.
A total of 23 were deployed through 1944-10.
Variants The SM-1 was a lighter version.  All 26 were given to the Royal Navy as Lend-Lease.


The SM was a fighter direction radar developed from the SCR-584.  It was rather heavy at 9 tons and so was only installed on carriers.  It could track in three dimensions with high accuracy and at close range, and it included a BM antenna for Identification Friend or Foe (IFF).  However, its distinctive beam, which was narrow both horizontally and vertically, made it unsuitable for air search.

References

Buderi (1998)

Friedman (1981)
Guerlac (1987)

Roberts (1982)


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