A five-six-port circuit comprising a waveguide on a main surface of a substrate. The hollow waveguide comprises probes arranged longitudinally inside the hollow waveguide arranged to contact the input port of one of three power detectors, whose output ports are arranged to contact the input port of one power detector. The output ports of the power detectors contact the conductor of an open waveguide which extends in parallel to the hollow waveguide. The probes are equidistantly spaced with a distance of L. The circuit also comprises three LP filters, each of which is connected to the conductor of the open waveguide at a position which corresponds to the position of one of the power detectors.