Improved finite element formulation for dielectric loaded waveguides

An efficient finite element method for analyzing the propagation characteristics and field pattern of a wide variety of inhomogeneously loaded waveguides is presented. The vector variational formulation including the suitable scalar potential is applied, and the incorporation of the Coulomb gauge ensures the uniqueness of the description. Owing to the correct description of the problem, spurious solutions do not appear anywhere in the whole region of the dispersion curves. The bisection method is employed for the solution of the generalized eigenvalue problem with sparse matrix techniques. The method is easy to program and the extension to 3-D cavities is straightforward. The disadvantage of the need for four scalar variables is offset by the robustness of the method