Numerical algorithm for the design of plane junction of two waveguides with arbitrary stepped boundaries of cross-section

The use of waveguides with nonstandard cross-sections or pieces of such waveguides as fragments of complicated diaphragms or frequency-selective surfaces is now a common practice in microwave engineering. Therefore the general key-building blocks that are oriented on arbitrary waveguide geometry, as well as the specialized key blocks for the fixed geometries are needed when developing the software for exact design of microwave devices. We discuss here the computation of the S-matrixes of a plane junction between two different waveguides with arbitrary stepped boundaries of cross-sections