Abstract: A Ka-band dual-polarized orthogonal mode transducer (OMT) for multi-probe antenna testing is designed and realized. A dual-ridge transition-branching structure of this OMT is employed. Utilizing waveguide equivalent impedance and impedance matching, key dimensions are determined and further optimized via simulations. Test results show that within the 26.5 GHz~40.0 GHz range, both output ports achieve a return loss better than 18 dB, the port isolation degree is greater than 52 dB, and the insertion loss is below 0.25 dB. Furthermore, its simple structure, lightweight design, and mass-producibility demonstrate superior performance.