Compact Orthomode Transducer Polarizer Based on a Tilted-Waveguide T-Junction

An alternative device to the well-known septum polarizer is proposed, which also provides the double function of an orthomode and a polarizer. It is based on a waveguide T-junction between a common dual-polarization waveguide and a tilted rectangular single-mode waveguide, and offers an intrinsically shorter geometry in the axial dimension, an advisable property when searching for compact antenna assemblies. The analysis of this new device is presented, along with the derivation and introduction of the S-parameters referred to the circularly polarized modes in the common waveguide. The working principle of the proposed T-junction is also explained in detail. A breadboard is designed, and its simulation and measurement results are presented. As a conclusion, the proposed device seems worthy of comparison in its electrical performances to the septum polarizer, showing some advantages in terms of geometrical dimensions and manufacturability.