Abstract: The present invention relates to a frequency converter circuit which can be used in a receiving apparatus for receiving a satellite broadcast and which is designed so that a local oscillation signal is distributed and supplied from a single local oscillator to mixer circuits of electric signal processing circuits of more than two systems and mixer diodes of the mixer circuits are biased with a dc current thereby always applying a biasing with the dc current even to the mixer diode of the electric signal processing circuit of the system which is not operated, and there are advantages of ensuring a stable operation, making possible a reduction in the size and weight and making favorable from the cost point of view.

Abstract: A frequency converter is constituted by an unobstructed circular waveguide unit through one end of which received signals are fed thereto and conveying signals in the TE11 mode, a rectangular waveguide unit having a rectangular waveguide microstrip line converter unit in its output end and conveying signals in the TE10 mode, a circular-rectangular waveguide converter unit connecting the output end of the circular waveguide unit and the rectangular waveguide unit to convert the mode of transmission of signals from the TE11 mode in the circular waveguide unit to a principal transmission mode TE10 in the rectangular waveguide unit, and a microwave integrated circuit extending in the direction of and being on the H-wall side of the circular-rectangular waveguide converter unit and the rectangular waveguide unit and connected to the rectangular waveguide-microstrip line converter unit for processing the received signals and delivering the received signals as signals of an intermediate frequency.