Many airborne doppler radars in use at present work with several beams in fixed directions and a pair of beams switched in sequence. In this paper, which was presented at the convention held in Dusseldorf in May 1961 (Journal, 14, 480), a new type of doppler radar is described in which a single beam is rotated around the vertical axis with a uniform angular velocity, keeping the depression angle constant. With this type of radar, combined with certain circuits in the transmitter-receiver, the frequency tracker and the data stabilizer, it is possible to measure the velocity of positive as well as negative values (including zero); it also allows easier functioning of data-stabilization. Further, a small and lightweight radar system may be constructed in this manner. This type of doppler radar is considered to be of particular use for small, low-speed aircraft.