Finite differences variable grid evaluation of TE modes in metallic ridge waveguides

A new general scheme for the FD approximation of the Laplace operator, based on a non-regular discretization, is discussed here. It allows to take into account in the FD scheme the boundary conditions, and therefore allows to use the exact shape of the boundary. As a consequence, the field distribution details can be more accurately modeled. This approach has been applied to mode evaluation in ridged waveguides, and allows a precise evaluation of the power capability of those guides.