The cross-section method

Abstract

The basic idea of the cross-section method is that the electromagnetic fields in an arbitrary nonuniform waveguide cross section are represented as a superposition of the waves of different modes propagating in forward and backward directions along an auxiliary straight uniform waveguide of the same cross section and with the identical distribution of e and μ. The coefficients of this superposition satisfy first-order ordinary differential equations. The general problem of the field derivation in a nonuniform waveguide is reduced in such a way to the problem of the fields in a uniform waveguide and to the solution of coupled-wave ordinary differential equations. Further, this method is employed for the basic types of nonuniform waveguides and for the more general case of combined nonuniformities.