A microwave transmission arrangement, comprising: a microwave circuit board including a dielectric carrier, and a first conductor pattern on a first side of the dielectric carrier, the first conductor pattern including a patch for radiating or receiving microwave signals, a patch line, and a first ground plane surrounding the patch and the patch feed line; microwave transceiver circuitry arranged on the microwave circuit board, the microwave transceiver circuitry having an output for providing microwave signals generated by the microwave transceiver circuitry and an input for receiving microwave signals, wherein the patch line is connected to at least one of the output and the input; an electrically conductive hollow waveguide extending from a first end to a second end and arranged to guide microwave signals radiated by the patch from the first end towards the second end, and/or guide received microwave signals from the second end towards the first end; and a separator sheet sandwiched between the microwave circuit board and the first end of the hollow waveguide, the separator sheet being configured to allow passage of microwaves between the patch and the hollow waveguide through the separator sheet, wherein the separator sheet is included in an encapsulation separating an encapsulated interior of the microwave transmission arrangement from an exterior outside the encapsulation, the patch, the patch line, and the microwave transceiver circuitry being in the encapsulated interior, and the hollow waveguide being in the exterior outside the encapsulation, characterized in that the separator sheet is in direct contact with the first side of the microwave circuit board and the first end of the hollow waveguide, so that there is no internal cavity between the microwave circuit board and the separator sheet. a microwave circuit board including a dielectric carrier, and a first conductor pattern on a first side of the dielectric carrier, the first conductor pattern including a patch for radiating or receiving microwave signals, a patch line, and a first ground plane surrounding the patch and the patch feed line; microwave transceiver circuitry arranged on the microwave circuit board, the microwave transceiver circuitry having an output for providing microwave signals generated by the microwave transceiver circuitry and an input for receiving microwave signals, wherein the patch line is connected to at least one of the output and the input; an electrically conductive hollow waveguide extending from a first end to a second end and arranged to guide microwave signals radiated by the patch from the first end towards the second end, and/or guide received microwave signals from the second end towards the first end; and a separator sheet sandwiched between the microwave circuit board and the first end of the hollow waveguide, the separator sheet being configured to allow passage of microwaves between the patch and the hollow waveguide through the separator sheet, wherein the separator sheet is included in an encapsulation separating an encapsulated interior of the microwave transmission arrangement from an exterior outside the encapsulation, the patch, the patch line, and the microwave transceiver circuitry being in the encapsulated interior, and the hollow waveguide being in the exterior outside the encapsulation, characterized in that the separator sheet is in direct contact with the first side of the microwave circuit board and the first end of the hollow waveguide, so that there is no internal cavity between the microwave circuit board and the separator sheet.