Radio detection and ranging, also known as radar, served an important part in the United States naval force during World War 2. On a general scale, one type of military radar is seen with detection radar. It creates an electronic map of all objects in all directions and at as great a distance away as possible.1 A significant component of radar was that it detected vessels on the surface and helped navigate ships during the night or weather conditions. Contrasting from the use of sonar, radar was primarily concerned with finding ships on the water surface. The emergence of microwave radar appeared in 1943. Microwaves are extremely high frequency radio waves that make up the spectrum of radio frequencies which are measured through the process of radar. The operation of SCR-584 radar in 1943 showed promise of efficiency when used for militaristic purposes. It was an automatic-tracking microwave radar developed by the MIT Radiation Laboratory during World War II that had a beam width of 4 degrees, and could track an aircraft with an accuracy of about 1.5 rn.2 When out on sea, it is essential for Destroyers to be equipped with a helicopter. Helicopters allow a smaller mode of faster transportation, or a bird’s eye view of a combat positioning when necessary in dire situations. The innovation in radar technology with the SCR-584, allowed navy ships equipped with the product to detect planes or helicopters in their range.3 This served as an important purpose as enemy planes posed as a threat as they could bomb or infiltrate surface ships. The German Navy used the Flettner Fl-282 helicopter stored in the conning tower of the submarines.4 Although it was a dangerous method of popping out the helicopter, the risk was taken in open waters. The United States Navy utilized radar technology to foresee incoming helicopters that may possibly damage US destroyers. Therefore, it showed that radar was a significant help in escaping the dangerous unrestricted submarine warfare the Germans played.
Another improvement in radar technology was seen with the emergence of SG radar in 1942, which created smaller antennas while retaining the same quality of performance. The smaller size created the possibility for radar technology to fit into navy ships. By 1943, a shorter wavelength of 8.6 cm was achieved which developed a larger range and resolution. Radar also participated in anti-submarine warfare regarding the fast German submarines. On October 23 1943, an unidentified object on the surface appeared for the USS Turner on the SG radar. The object was soon identified as a German enemy submarine and immediate fire was taken. The U.S.S. Turner was able to drastically damage the submarine.5 A small victory was seen for the United States Navy with the technology of SG radar. By detecting a threat, the safety of the ship was not compromised and there was now one less German submarine to worry about for the Allies. The innovation of SG radar made it possible for the Turner to detect the submarine first because of the improved antenna which produced an expanded range.
Fire Control Radar
The Navy consists of many high tech weapons that are used for offensive and defensive purpose., During World War 2, the United States paired with the Allies were continuously on the offensive having the upper hand. Although at sea, the German U-boats proved to have speed and sneakiness so the United States used weapons with the access they had to technology in order to outsmart and destroy the enemy. Fire Control radar is a form of implementing radar as a tactical use.6 The radio waves help locate the precise position of a previously detected target. As a result, the weapon aboard the ship can aim at a particular region without having to physically view the target. This allowed far range missiles to be shot if it could not be seen with the naked eye, and as a guiding tool for when weapons are needed to be used at night in the dark.7 The radio waves spread out and bounce back on the surface, showing the distance of the target while calculating the time, distance and direction the object is in.8
Military radar was distinguished by different bands during World War 2 including the availability of L, S, C, X, Ku, and K bands. Each had unique frequencies as seen with the L band ranging from 1-2 GHz, the S band ranging from 2-4 GHz, the C band ranging from 4-8 GHz, the X band ranging from 8-12 GHz, the Ku band ranging from 12-18 GHz and the K band ranging from 18-27 GHz.9 Modified from the SG radar, SJ radar was introduced into the war environment in 1942. Replacing the outdated version of SD radar, the SJ radar was the second type of radar deployed on submarines. Similar to the use of SG radar, this particular type of radar had the ability to be placed inside submarine hatches for installation and designed to lie close to the curved hulls. This made it possible for directional and distance information to become available for submarines. As it was radar and not sonar, it’s limitations stopped at the water surface. During World War 2 the Navy ship, USS Cobia, portrayed the utilization of this specific radar. It operated on SJ radar to detect and navigate through the waters when it found an enemy object in its path. It was classified as a minelayer, common naval term used to identify naval ships which deploy sea mines. On January 14, the USS Cobia sank the minelayer Yurishima off the southeast coast of Malaya when it appeared on their radar screen.10 The ability to identify the obstacles in the navigation of open waters presented an opportunity for the United States navy to gain an advantage by eliminating a potential threat. The utilization of SJ radar was also used as a communications device by sending radar signals between two submarines. As mentioned before, the United States Navy consisted of many submarines that greatly contributed to the success of the war for the Allies. The SJ radar was used in the naval tactic of operating in a wolf pack. This use of SJ radar was specifically seen in the fight with the Japanese as it was used to halt their shipping and offensive naval action on sea during the Battle of the Atlantic. This technique worked as three ships would patrol together, creating stronger power in the amount of strength they carried. The radio waves and pulses from radar develop a line of communication in which the ships involved in the wolfpack were able to speak to each other and corner the enemy.11
1 Naval Sonar. U.S. Navy Training Publications Center, 1953.
2 “Radar during World War II.” Radar during World War II – Engineering and Technology History Wiki, Engineering and Technology History Wiki (ETHW), 25 Sept. 2015.
3 Campbell, 68
4 Bjorkman, James. “German Helicopters.” World War II in Pictures: German Helicopters, 1 Jan. 1970.
5 Principato, Lawrence. “THE USS TURNER GOES DOWN.” USS Turner, Treasure Quest Magazine.
6 Pekelney, Richard. Fire control fundamentals: section-50 rating specialization information instruction sheets. U.S. G.P.O., 1954.
7 Pekelney, 16
8 Pekelney, 18
9 Sawicki, Donald S. Radio and Radar Frequency Bands, 2015.
10 Friedman, Norman. U.S. submarines through 1945: an illustrated design history. Naval Institute Press, 1995.
11 Potter, E. B., et al. Sea power a naval history. Naval Institute Press, 1987.