Radar apparatus (10) that includes a millimeter wave radar transmitter (11) comprising a flood beam antenna (17), and a radar signal processor (30) for processing radar return signals to produce radar output signals. An RF sensor (20) comprising a receive antenna (21) includes a plurality of antenna elements (21a), a plurality of mixers (22) respectively coupled to outputs of the plurality of antenna elements (21a) and coupled to the transmitter (14) by means of a coupler (26), a plurality of filter circuits (23) respectively coupled to outputs of the plurality of mixers (22), a multiplexer (24) coupled to outputs of the plurality of filter circuits (23) that comprises as a multiple input, single output switch (25) for sequentially outputting video signals derived from radar signals received by each of the receive antenna elements (21a), and a lens (27) for imaging radar returns onto each of the plurality of antenna elements (21a). The heart of the present invention is a heterodyne receive antenna (21) that may be used in many applications, including radiometric or radar applications, and the like. The present invention provides for a 35-300 GHz millimeter wave electronic scanning sensor (20) for use in collision avoidance applications, and the like.