RADSCAN - A novel conically scanning tracking feed

The SCR-584 radar, which was developed as one of the first tracking systems at the beginning of 1942, used a conically scanning technique. A unique conically scanned feed, called RADSCAN, which has but one moving part and no rotary joint, has now been developed by an American company. A pair of stationary orthogonal printed circuit dipoles are used to excite the TE11 mode in the rotating circular waveguide. The displacement of the phase center of the circular waveguide from the boresight axis causes the conical scanning. The single-channel monopulse technique is discussed, and a comparison of RADSCAN and the single channel monopulse is conducted. Attention is given to aspects of reliability, low-angle tracking, beam crossover variation with frequency, cross talk, error modulation, and boresight shift with frequency.