A radar sensor module includes a substrate, at least one transmit antenna formed on a surface of the substrate, and at least one receive antenna formed on the surface of the substrate. A radome is disposed over the surface of the substrate and the at least one transmit antenna and the at least one receive antenna, such that a gap is located between the surface of the substrate and an underside of the radome in which a portion of radiation emitted from the at least one transmit antenna can propagate. At least one trench is formed in the underside of the radome and is electromagnetically coupled to the gap, the at least one trench being sized, shaped and positioned with respect to the gap such that the portion of radiation emitted from the at least one transmit antenna is substantially prevented from propagating toward the receiving antenna.