Waveguide based five or six port circuit

A five-port circuit comprising a hollow waveguide mounted with a contacting surface on a first main surface of a non-conducting substrate, the hollow waveguide comprising an input port at its one end and a matched load at its other end, the five-port circuit further comprising three probes arranged along a longitudinal extension of the hollow waveguide and three power detectors, with each of said probes being arranged to contact the input port of one of said power detectors, with the output ports of said power detectors being arranged to contact the conductor of an open waveguide which is also comprised in the five-port circuit and which extends in parallel to the hollow waveguide with an input port at its one end and a matched load at its other end, in which five-port circuit the probes are equidistantly spaced with a distance L between neighbouring probes which corresponds to an electrical length of θ, defined as θ=2πL/λ, where λ, is the wavelength which corresponds to the operational frequency of the five-port circuit, said five-port circuit also comprising three low pass filters, each of which is connected with its input port to the conductor of the open waveguide at a position which corresponds to the position of one of the power detectors, so that each probe is arranged in a straight line with one of the power detectors and one of the low pass filters, with the output ports of the low pass filters being arranged to be used as the output ports of the five-port circuit and with the input ports of the hollow waveguide and the open waveguide being arranged at distal ends from each other.