Abstract: According to the invention, a monostatic FMCW radar sensor for a vehicle for detecting objects is proposed in which at least one antenna feed in combination with a dielectric lens is embodied for both transmitting and receiving a corresponding echo signal. At least one antenna feed is connected to a ring mixer via a ratrace ring or double ratrace ring, so that an expensive circulator can be dispensed with. The high-frequency structure is advantageously embodied in planar microstrip form. A plurality of transmission and reception antennas are focused via one common lens.