SJ radar
Encyclopedia
SJ radar was the name of a type of S-band (10-cm) radar
set used on United States
submarine
s during the Second World War. The widespread use of the SJ radar, combined with the very low use of radar in the Imperial Japanese Navy
gave great operational flexibility to the U.S. Navy's submarine campaign in the Pacific Ocean
.
The first prototype SJ was deployed in December 1941, but it was mid-1942 before they became common equipment. SJ radar was on all submarines by early 1943. The SJ was the second type of radar deployed on submarines during the war, representing a substantial improvement over the previous SD radar. The SJ was a variant of the SG surface search radar used on surface warships, contained in sets capable of fitting through submarine hatches for installation and designed to lie close to the curved hulls.
The SJ provided directional information, provided highly accurate distance information, and provided information about surface contacts as well as low-flying aircraft
.
The SJ radar was even used as a communications device. When used with a telegraph key, the SJ radar could send signals on a point-to-point basis between two submarines operating in a wolf pack. The directionality of the antenna and the short range provided relatively high security for this transmission.
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
set used on United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
submarine
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...
s during the Second World War. The widespread use of the SJ radar, combined with the very low use of radar in the Imperial Japanese Navy
Imperial Japanese Navy
The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...
gave great operational flexibility to the U.S. Navy's submarine campaign in the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
.
The first prototype SJ was deployed in December 1941, but it was mid-1942 before they became common equipment. SJ radar was on all submarines by early 1943. The SJ was the second type of radar deployed on submarines during the war, representing a substantial improvement over the previous SD radar. The SJ was a variant of the SG surface search radar used on surface warships, contained in sets capable of fitting through submarine hatches for installation and designed to lie close to the curved hulls.
The SJ provided directional information, provided highly accurate distance information, and provided information about surface contacts as well as low-flying aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
.
The SJ radar was even used as a communications device. When used with a telegraph key, the SJ radar could send signals on a point-to-point basis between two submarines operating in a wolf pack. The directionality of the antenna and the short range provided relatively high security for this transmission.