An orth-mode transducer (OMT) assembly, including an OMT common port, an OMT feeder, and a polarization separated core. An input end of the OMT common port is connected to a single polarization antenna, one end of the OMT feeder is connected to an output end of the OMT common port, and an other end of the OMT feeder is connected to the polarization separated core, the OMT feeder has a tubular structure, and horizontal and vertical axes of an inner wall cross section of the OMT feeder are unequal, or a tuning rod is disposed in a tube of the OMT feeder and is perpendicular to an extension direction of the tube, and a vertical polarization port and a horizontal polarization port are disposed in the polarization separated core, the vertical polarization port transmits a vertical polarization wave, and the horizontal polarization port transmits a horizontal polarization wave.