A microwave communications device (100; 510), comprising: a first converting module, a second converting module, an orthomode transducer; the first converting module and the second converting module are configured to perform mutual conversion between a baseband signal or an intermediate frequency signal and a microwave signal, wherein microwave signals received or output by the first converting module and microwave signals received or output by the second converting module respectively have a first polarization direction and a second polarization direction, and the first polarization direction and the second polarization direction are the same or perpendicular to each other; and the orthomode transducer is configured to perform separation and synthesis of orthogonally polarized microwave signals, wherein, the orthomode transducer includes a first waveguide port, a second waveguide port, and a third waveguide port; wherein polarization directions of microwave signals received or output by the first waveguide port and microwave signals received or output by the second waveguide port are perpendicular to each other; characterized in that, the first converting module is connected to the first waveguide port, the second converting module is connected to the first waveguide port or the second waveguide port by using the waveguide switch, and an antenna system is connected to the third waveguide port; the waveguide switch is configured to selectively switch between a first connection position and a second connection position, and is used for polarization conversion between microwave signals, so that: when the waveguide switch is in the first connection position, the waveguide switch is connected to the second converting module and the first waveguide port of the orthomode transducer, and a received or output microwave signal has the first polarization direction; when the waveguide switch is in the second connection position, the waveguide switch is connected to the second converting module and the second waveguide port of the orthomode transducer, and a received or output microwave signal has a polarization direction perpendicular to the first polarization direction. a first converting module, a second converting module, an orthomode transducer; the first converting module and the second converting module are configured to perform mutual conversion between a baseband signal or an intermediate frequency signal and a microwave signal, wherein microwave signals received or output by the first converting module and microwave signals received or output by the second converting module respectively have a first polarization direction and a second polarization direction, and the first polarization direction and the second polarization direction are the same or perpendicular to each other; and the orthomode transducer is configured to perform separation and synthesis of orthogonally polarized microwave signals, wherein, the orthomode transducer includes a first waveguide port, a second waveguide port, and a third waveguide port; wherein polarization directions of microwave signals received or output by the first waveguide port and microwave signals received or output by the second waveguide port are perpendicular to each other; characterized in that, the first converting module is connected to the first waveguide port, the second converting module is connected to the first waveguide port or the second waveguide port by using the waveguide switch, and an antenna system is connected to the third waveguide port; the waveguide switch is configured to selectively switch between a first connection position and a second connection position, and is used for polarization conversion between microwave signals, so that: when the waveguide switch is in the first connection position, the waveguide switch is connected to the second converting module and the first waveguide port of the orthomode transducer, and a received or output microwave signal has the first polarization direction; when the waveguide switch is in the second connection position, the waveguide switch is connected to the second converting module and the second waveguide port of the orthomode transducer, and a received or output microwave signal has a polarization direction perpendicular to the first polarization direction.