Abstract: The surveillance radar device comprises, in combination, a fixed antenna for providing electronic scanning of space in bearing in the horizontal plane, a transmit source and microwave frequency transmit/receive means with a circulator, a transmit channel, a receive channel and means for subdividing the receive channel into a sum signal and at least one difference signal. A first and a second receiver element with frequency change respectively receive the sum and difference signals, and provide numerically coded outputs. Processing means process numerical signals from the first and second receiver elements for the radar detection of objects in the zone under surveillance.