A system comprising: a waveguide having a body with a first end having an opening, and a printed circuit board, PCB, having a bottom side and an opposed top side, wherein the PCB comprises a ground layer, a dielectric material layer and a signal layer arranged in a layer stack from the bottom side to the top side of the PCB, wherein the dielectric material layer is arranged between the ground layer and the signal layer, wherein the signal layer comprises a coupling pad and a first and a second output transmission line (116, 118) both connected to the coupling pad; wherein the PCB further comprises a non-conducting slot in the ground layer; wherein the PCB further comprises an electric wall galvanically connecting the coupling pad through the dielectric material layer to the ground layer; wherein the first end of the waveguide is arranged on the bottom side of the PCB and is galvanically connected with the ground layer; wherein the opening, the non-conducting slot and the coupling pad are aligned such that in a stacking direction of the layer stack the opening, the non-conducting slot and the coupling pad at least partially overlap; wherein each of the layers of the PCB is provided with a through-hole configured for accepting a screw for screwing the PCB to the waveguide and the through-holes of each layer are aligned such that in the stacking direction the through-holes coincide, thereby forming a hole extending from the top side of the PCB to the bottom side of the PCB, wherein the hole extending from the top side of the PCB to the bottom side of the PCB does not overlap with the opening in the waveguide, the non-conducting slot and the coupling pad; wherein the through-holes are metalized and form a part of the electric wall; wherein the through hole of the signal layer, and therefore the hole extending from the top side of the PCB to the bottom side of the PCB, is arranged in close proximity to the coupling pad, so that a distance between a center axis of the through hole of the signal layer to the symmetry point of the waveguide opening is between 60% to 300% of a width of the opening of the waveguide, preferably between 100% to 250% of the width of the opening of the waveguide; wherein the system further comprises a stepped impedance transformer attached to the first end of the waveguide between the first end of the waveguide and the bottom side of the PCB. a waveguide having a body with a first end having an opening, and a printed circuit board, PCB, having a bottom side and an opposed top side, wherein the PCB comprises a ground layer, a dielectric material layer and a signal layer arranged in a layer stack from the bottom side to the top side of the PCB, wherein the dielectric material layer is arranged between the ground layer and the signal layer, wherein the signal layer comprises a coupling pad and a first and a second output transmission line (116, 118) both connected to the coupling pad; wherein the PCB further comprises a non-conducting slot in the ground layer; wherein the PCB further comprises an electric wall galvanically connecting the coupling pad through the dielectric material layer to the ground layer; wherein the first end of the waveguide is arranged on the bottom side of the PCB and is galvanically connected with the ground layer; wherein the opening, the non-conducting slot and the coupling pad are aligned such that in a stacking direction of the layer stack the opening, the non-conducting slot and the coupling pad at least partially overlap; wherein each of the layers of the PCB is provided with a through-hole configured for accepting a screw for screwing the PCB to the waveguide and the through-holes of each layer are aligned such that in the stacking direction the through-holes coincide, thereby forming a hole extending from the top side of the PCB to the bottom side of the PCB, wherein the hole extending from the top side of the PCB to the bottom side of the PCB does not overlap with the opening in the waveguide, the non-conducting slot and the coupling pad; wherein the through-holes are metalized and form a part of the electric wall; wherein the through hole of the signal layer, and therefore the hole extending from the top side of the PCB to the bottom side of the PCB, is arranged in close proximity to the coupling pad, so that a distance between a center axis of the through hole of the signal layer to the symmetry point of the waveguide opening is between 60% to 300% of a width of the opening of the waveguide, preferably between 100% to 250% of the width of the opening of the waveguide; wherein the system further comprises a stepped impedance transformer attached to the first end of the waveguide between the first end of the waveguide and the bottom side of the PCB.