3D Printed and Metallized Ka-Band Orthomode Transducer for Polarimetric Radar Applications

An orthomode transducer allows the combination or separation of orthogonal waveguide modes. This paper presents a stepped orthomode transducer (OMT) for Ka-band, developed for polarimetric radar applications to reduce the number of antenna elements. The OMT is produced by stereolithography 3D printing and then manually metallized with conductive paint. A CST simulation model is presented, which considers mechanical and manufacturing related constraints such as electrical conductivity and surface roughness. For applying the conductive paint, a split block design with two halves and a constructive gap, which was also accounted in the simulation, is developed. The impact on the performance compared to a lossless and monolithic structure is analyzed. A sample of the 3-port OMT is fabricated and measurements are performed. The comparison of the simulated and measured S-parameters shows that the designed structure works as intended and the correspondence of the model with reality is sufficient.