Aerial assembly and pedestal from SCR 584 tracking radar, c.1944

The SCR 584 was an American 10-cm radar whose primary purpose was to follow a target automatically and supply information on its position, for use with anti-aircraft guns. The equipment was housed in a large trailer, with the aerial pedestal on the roof.

The aerial beam was slightly offset from the axis of the reflector, and was rotated about that axis by spinning the dipole feed assembly. As a result, the echo from any target not exactly on the axis varied in strength as the dipole rotated.

The timing on the variation conveyed the direction of the error in the aerial’s bearing, enabling the aerial-positioning system to ‘track’ the target.