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 . <EOS>