A method for the determination of modal fields in waveguides with arbitrary cross-section

A numerical method for the determination of modal fields and propagation constants of metallic waveguides with arbitrary cross-section is developed, based on dyadic Green's functions and the moment method. It results in a representation of the modal fields as a series over orthogonal functions (the eigenfunctions of a rectangular waveguide, circumscribing the waveguide with arbitrary cross-section). Application to ridge, triangular and circular waveguides shows the accuracy of the method.