Waveguide coupling device for a radar sensor, comprising: a waveguide for emitting and/or receiving a radar signal; and a high-frequency substrate having at a first end at least one input conductor for feeding at least one excitation wave into the high-frequency substrate, at a second end opposite the first end a radiation region for coupling the excitation wave out of the high-frequency substrate, and a waveguide coupled to the input conductor and the radiation region; wherein an excitation end of the waveguide is arranged on the radiation region of the high-frequency substrate such that the excitation wave can be coupled into the excitation end of the waveguide via the radiation region of the high-frequency substrate; wherein the waveguide comprises at least a first excitation element and a second excitation element, each of which is disposed at the excitation end in an interior volume of the waveguide and extends in parallel to the longitudinal direction of the waveguide; characterized in that the first excitation element has a first length measured in the longitudinal direction of the waveguide and the second excitation element has a second length dimensioned in the longitudinal direction of the waveguide, which is different from the first length of the first excitation element, so that at least a first resonant wave with a first resonant frequency and a second resonant wave with a second resonant frequency is excitable via the excitation wave at the first excitation element and the second excitation element, which are superimposable in the waveguide to form the radar signal, wherein the radiation area is limited by vias and/or the waveguide has two cavities located from either side of the second excitation element. a waveguide for emitting and/or receiving a radar signal; and a high-frequency substrate having at a first end at least one input conductor for feeding at least one excitation wave into the high-frequency substrate, at a second end opposite the first end a radiation region for coupling the excitation wave out of the high-frequency substrate, and a waveguide coupled to the input conductor and the radiation region; wherein an excitation end of the waveguide is arranged on the radiation region of the high-frequency substrate such that the excitation wave can be coupled into the excitation end of the waveguide via the radiation region of the high-frequency substrate; wherein the waveguide comprises at least a first excitation element and a second excitation element, each of which is disposed at the excitation end in an interior volume of the waveguide and extends in parallel to the longitudinal direction of the waveguide; characterized in that the first excitation element has a first length measured in the longitudinal direction of the waveguide and the second excitation element has a second length dimensioned in the longitudinal direction of the waveguide, which is different from the first length of the first excitation element, so that at least a first resonant wave with a first resonant frequency and a second resonant wave with a second resonant frequency is excitable via the excitation wave at the first excitation element and the second excitation element, which are superimposable in the waveguide to form the radar signal, wherein the radiation area is limited by vias and/or the waveguide has two cavities located from either side of the second excitation element.