The SCR-584 was a microwave radar which was designed and manufactured by the MIT Radiation Laboratory during World War II. Extremely advanced for the time it was introduced, the SCR-584 could achieve high accuracy using a conical scanning system, in which the beam is rotated around the antenna's axis to find the maximum signal point, thus indicating which direction the antenna should move in order to point directly at the target. This system was not new, having been introduced on the German Würzburg radar in 1941. Nevertheless, the designers of the SCR-584 developed the system much further, adding an automatic tracking mode. Once the target had been detected and was within range, the system would keep the radar pointed at the target automatically, driven by motors mounted in the antenna's base. "SCR-584" stood for "Signal Corps Radio #584".
The SCR-584 was first used in combat at Anzio in February 1944, where it played a key role in breaking up the Luftwaffe's concentrated air attacks on the confined beachhead. The SCR-584 was no stranger to the front, where it followed the troops, being used to direct aircraft, locate enemy vehicles, and track the trajectories of artillery shells, both to adjust the ballistic tables for the 90 millimeter guns, and to pinpoint the location of German batteries for counter-battery fire. The SCR-584 was not, however, used in the rapidly-shifting very front lines, where lighter, less accurate, radars such as the AN/TPS-1 were used. The SCR-584 replaced the earlier and much more complex SCR-270 as the US Army's primary anti-aircraft gun laying system as quickly as they could be produced. In service it proved to be an outstanding system, much more advanced than any other battlefield radar system deployed during the war.