  An eigenmode projection technique (EPT) is developed and employed to solve
problems of electromagnetic resonance in closed cavities and scattering from
discontinuities in guided-wave structures. The EPT invokes the eigenmodes of a
canonical predefined cavity in the solution procedure and uses the expansion of
these eigenmodes to solve Maxwell's equations, in conjunction with a convenient
choice of port boundary conditions. For closed cavities, resonance frequencies
of arbitrary-shaped cavities are accurately determined with a robust and
efficient separation method of spurious modes. For waveguide scattering
problems, the EPT is combined with the generalized scattering matrix approach
to solve problems involving waveguide discontinuities with arbitrary dielectric
profiles. Convergence studies show stable solutions for a relatively small
number of expansion modes, and the proposed method shows great robustness over
conventional solvers in analyzing electromagnetic problems with inhomogeneous
materials.
