A 3D-Printed Lightweight Compact Wideband Dual-Polarized Feed Module for Sub-THz Applications

A sub-Terahertz (THz) three-dimensional (3D) printed lightweight compact wideband dual-polarized feed module using an innovative asymmetric wideband orthomode transducer (OMT) is proposed. The OMT is based on a T-shaped waveguide mode separator that maintains both simplicity and compactness. A novel T-shaped to square waveguide transition is developed to ensure satisfying impedance matching and waveform transforming features over a wide band for the fundamental TE10/TE01 mode, but it does not excite the undesirable TE11 mode within the operating band. Therefore, the bandwidth limitation of the OMT with asymmetric geometries, caused by the restricted single-mode bandwidth of the square waveguide, can be overcome. Benefitting from the use of three-dimensional (3D) micro-printing technology, the feed module consisting of the OMT and a pyramidal horn radiator is realized in one piece. Experimental results demonstrate that the feed module achieves a superior bandwidth of 53% (from 126 to 219 GHz) with stable radiation and an isolation of more than 50 dB between the two input ports. Its geometry with a total weight of only 0.35 g is also significantly smaller in volume compared to the previously reported sub-THz and THz designs. Because of the simple geometry and outstanding performance, the feed module is an attractive candidate for advanced sub-THz applications.