A mixed asymptotic and FD method for the EM field modelling in quasi-optical devices

A method for modeling the electromagnetic (EM) fields in quasi-optical devices is presented. It is based on the ray tracing technique with field refinement by the geometrical theory of diffraction and FD method. The last is applied in regions where it is hard to obtain asymptotic solutions. A comparison with the adaptive mesh FEM is presented and the ways in which performance is improved are outlined.