Single and coupled transmission line models of open dielectric waveguides

A general procedure is outlined for obtaining single or coupled transmission line models to represent the propagation of surface wave modes in open dielectric waveguides. The procedure uses a homogeneous electrically or magnetically walled waveguide having the same dimensions as the dielectric in the surface waveguide to produce a set of orthogonal eigenfunctions. These eigenfunctions are then projected upon Maxwell's equations resulting in a system of transmission lines coupled together through a wave immittance. This wave immittance represents the ratio of a longitudinal and a transverse field component in the surface waveguide at the dielectric-air interface.