Polarisation-source formulation of electromagnetism and dielectric-loaded waveguides

A general formulation is presented for the diffraction of arbitrary fields by bodies exhibiting arbitrary variations of permittivity, permeability and conductivity. Piecewise-continuous and perfectly conducting bodies are included. The general solution to any diffraction problem is given as a single integral equation. Special attention is paid to time-harmonic fields and piecewise-constant bodies. This is illustrated by the computation of the cutoff characteristics of hollow, conducting waveguides of arbitrary cross-section loaded with dielectric tubes. Numerical results are presented for a square waveguide loaded with a solid dielectric rod. Experimental results are also reported.