A Ka-Band Wideband Monolithically Metallic 3-D Printed Turnstile Junction Orthomode Transducer with Shaped Internal Profile

This paper presents design and implementation of a Ka-band wideband turnstile-junction-based waveguide orthomode transducer (OMT). The OMT is composed of turnstile and Y-shape junctions that are connected by twisted waveguides. These constituent parts are properly arranged to form a compact OMT architecture. More significantly, sharp corners and edges inside these parts are shaped with fillets, resulting in smooth internal profile that exhibits enhanced structural compatibility with additive manufacturing technology. Two OMT prototypes are devised for experimental validation in horizontal and vertical orientations of polarization. They are monolithically 3-D printed with an aluminum alloy AlSi10Mg and their RF performance at Ka band is measured. The engineered OMTs demonstrate port return loss of mostly >15 dB, average transmission loss of 0.5–1.0 dB, port isolation of >20 dB, and polarization isolation of >19 dB. This work has exemplified importance of geometrical shaping in the application of 3-D printed complex waveguide structures.