Computation of mode bases for waveguides with complicated cross-sections

At the present time the mode-matching technique (MMT) is one of the most popular and effective methods of waveguide discontinuities analysis and synthesis. With this method, an initial waveguide structure is separated into a set of regular subregions, whose mode bases (cutoff frequencies, natural mode field functions, and mode norms) are known or can be calculated. The MMT is applied to analyse both waveguide mode bases and plane junctions. However the MMT has limited flexibility. If the waveguide has not a separable cross-section its basis calculation is impossible directly with MMT. Methods of calculating the waveguides of complicated cross-section are necessary here, for example, the finite difference method, the finite elements method, integral equation methods and others. Hence a combination of these methods and MMT provides a way of designing waveguide discontinuities with arbitrary shape elements. In the work being presented a new method of mode bases calculation for the waveguides of complicated cross-sections is proposed.