Abstract: A receiver for counterclockwise and clockwise circularly polarized microwave signals of the type comprising a receiving antenna with a feeder system, a polarization converter, a polarization filter and a circuit for converting the microwave signals of both polarization directions from the high frequency to the intermediate frequency plane. A portion of the feeder waveguide belonging to the feeder system of the receiving antenna is designed as a bandpass filter which is effective for both polarization directions. A microstripline substrate, which carries the frequency converting circuit, is connected with the output of the feeder waveguide and is provided with an arrangement for coupling in the energies of the waveguide modes of both polarization directions. The polarization converter is either directly integrated in the feeder waveguide or the polarization conversion is effected by coupling the waveguide modes into the microstripline circuit.

Abstract: A method for detecting a predetermined code word contained in received signals in a transmission system which operates with a four-phase type of modulation at the transmitter and coherent demodulation at the receiver, the code word being transmitted only as signals in two phases which are 180.degree. apart and the received signals being divided into orthogonal voltage components during demodulation, which method includes selecting that one of the sum and difference of the voltage components which has the larger absolute magnitude value, and evaluating the received signal in accordance with the algebraic sign of that one of the sum and difference which is thus selected.