Uniaxially Symmetrical T-Junction OMT with 45-Degree Tilted Branch Waveguide Ports

Abstract

A T-junction Ortho-Mode-Transducer (OMT) is known as one of waveguide components that separate two orthogonal linear polarizations in the same frequency band. One of the advantages of the T-junction OMT is short axial length. However, the two rectangular ports need to be orthogonal, and it is difficult to realize the wideband performances for its asymmetry. We propose a uniaxially symmetrical T-junction OMT to realize the wideband performances. The proposed configuration has two branch waveguides which are 45-degree tilted to the short circuit. The uniaxially symmetrical configuration enables to realize the same performances for the two ports, and the impedance matching is easier compared to the conventional one. The polarization separation principle can be explained using principles of Ortho-Mode-Junction (OMJ) and turn-style OMT. The design results demonstrated a return loss of 25dB, a polarization isolation of 30dB, an interterminal isolation of 21dB and a loss of 0.25dB, with a bandwidth of 15% in the K-band for satellite communication systems. The OMT was then fabricated as a single piece via 3D printing and evaluated against the calculated performance indices.