Research on a Millimeter-wave Full-band Ortho-mode Transducer

An improved Ka full-band ortho-mode transducer is proposed based on the turnstile junction for the ultra-wideband transceiver applications. To improve the performance of broadband and reduce the structure complexity, a three-step E-plane waveguide bend and a multi-step power combiner are designed to implement the entirely E-plane bend configuration. The length de-sign criterion of the connecting waveguides is analyzed, which ensures that the electrical lengths of the two ortho-mode propagation paths are consistent. Benefiting from the entirely E-plane design, the structural symmetry is implemented and the turnstile junction can be machined in a complete block, requiring neither strict alignment nor a high level of mechanical tolerances. The number of the fabricated superimposed blocks is no more than four. The measured return loss and the isolation between the two orthogonal modes is 20 dB and 50 dB respectively, over 26 GHz~ 40 GHz (42%) . The insertion loss of a single ortho-mode transducer is below 0. 4 dB, and the phase difference between the two modes is below 5°. The results demonstrate a good agreement between the full-wave simulations and measurements.