Design and Alignment Tolerance Analysis of an E-band Turnstile Orthomode Transducer

Orthomode transducers (OMT) are a key passive microwave device in satellite and wireless communication systems. Their function is to combine or separate two orthogonal signals received and transmitted by dual-polarization. The main structure of the orthomode transducer considered in this paper is the turnstile junction. The design of the OMT combines a turnstile junction, E-plane bend, H-plane bend, and Y-junction, and it exhibits good return loss, high isolation, and low cross-polarization. We discuss its tolerance (< 0.05 mm) by analyzing misalignment between its top, middle, and bottom sections. The transducer does not exhibit significant spikes in response to high order model reflection but an offset of 0.1 mm results in obvious spikes.