An extended Huygens' principle for modelling scattering from general discontinuities within hollow waveguides

The modal fields, generalized scattering matrix (GSM) theory and dyadic Gre en's functions relating to a general uniform hollow waveguide are briefly r eviewed in a mutually consistent normalization. By means of an analysis lin king these three concepts, an extended version of the mathematical expressi on of Huygens' principle is derived, applying to scattering from an arbitra ry object within a hollow waveguide. The integral-equation result expresses the total field in terms of the incident waveguide modal fields, the dyadi c Green's functions and the tangential electromagnetic field on the surface of the object. It is shown how the extended principle may be applied in tu rn to perfect conductor, uniform material and inhomogeneous material object s using a quasi method of moments (MM) approach, coupled in the last case w ith the finite element method. The work reported, which indicates how the G SM of the object may be recovered, is entirely theoretical but displays a c lose similarity with established MM procedures. Copyright (C) 2001 John Wil ey & Sons, Ltd.