S-matrix of a waveguide tee with a dividing septum overlapping with the tee interior

Orthomode transducer (OMT) aiming to divide the signals of orthogonal polarizations, is an important part of antenna circuits of modern communication systems. One of the most popular solutions to separate two linear cross-polarized signals is based on the tee in the square waveguide. The design of such a device is hampered by a lack of efficient mode-matching solution for the main key-element. Therefore it is required to use very time-consuming numerical algorithms based on one or another kinds of lattice methods. The goal of this report is to extend the area of mode-matching applications on the tees with inserts in tee interiors by the example of key-elements of OMT. New mode matching based algorithm for S-matrix calculation provides very high accuracy at low CPU time and enables the possibility of quick optimization of the OMT geometry as a whole