graduate

SK Air Search Radar


Photograph of SK naval radar
National Archives #19-N-49139


Specifications:


Wavelength 1.5 m
Pulse Width 5 microsecond
Pulse Repetition Frequency     
60 Hz
Scan rate 4.5 rotations per minute
Power 200 kW
Range 100 nautical miles (190 km) on bomber
75 nautical miles (140 km) on fighter
30 nautical miles (55 km) on battleship
13 nautical miles (24 km) on destroyer
Antenna
17' square 6x6 dipole "mattress" array
Scope
12" (30cm) plan position indicator (PPI) with 20, 75, and 200 nautical mile (37, 140, and 370 km) distance scales
5" (13cm) "A" scope with 15, 75, and 373 nautical mile (28, 140, and 690  km) distance scales
Accuracy 100 yards/1 degree
90 meters/1 degree
Resolution 1800 feet/10 degrees
550 meters/10 degrees
Weight 4900 lbs (2200 kg), of which 2330 lbs (1060 kg) was the antenna
Production: 250 between 1/43 and 4/44.  
An additional 75 SK-2 were installed between 4/44 and 12/44.


Also known as CXFA, the SK was an air search radar developed from the SC-2 with a CXAM antenna.  Identification Friend or Foe (IFF) was provided by a Bl-5 antenna atop the main SK antenna.

Like all long-wavelength seaborne radar, SK had a tendency to reflect off the sea surface to produce self-interference (Lloyd's mirror effect) that created "nulls" in its search pattern at certain altitudes. This made it difficult to maintain contact with approaching aircraft, which often disappeared into a "null" for several miles.This was a significant liability during the kamikaze campaign, when SK was the most numerous air search radar with the fleet and microwave radars less subject to nulls did not yet have the necessary altitude coverage for air search.


References

Buderi (1998)

Friedman (1981)
Historic Naval Ships Association (accessed 2009-7-3)

Roberts (1982)

Stern (2010)


Valid HTML 4.01 Transitional