Low-profile high-performance orthogonal mode coupler

The invention discloses a low-profile high-performance orthogonal mode coupler, which comprises a circular waveguide, an E-plane matching waveguide, an E-plane rectangular waveguide, an H-plane matching waveguide, an H-plane rectangular waveguide, a semi-cylindrical matching waveguide and a plurality of impedance adjusting blocks, wherein the impedance adjusting blocks are gradually increased from top to bottom; the OMT is low in profile, very simple in structure and easy to process; the performance is excellent, the standing wave bandwidth of each port with the VSWR smaller than or equal to 1.2 is higher than 20%, the standing wave of the circular waveguide port in the working frequency band is even lower than 1.06, and the isolation degree of the ports in the working frequency band is higher than 65 dB; the device has the advantages of compact and simple structure and excellent performance, is very suitable for batch production, and has good popularization value.