Adaptive solution space projection in conjunction with finite-element eigenfunction expansion for fast and robust wideband simulation of microwave devices

The eigenfunction expansion technique has been successfully applied to analyze various waveguide discontinuity problems, in which all of the ports are homogeneous and only TE and TM modes need to be taken into account. Modal solutions at each port are used as a boundary condition for the purposes of truncating a computational domain and exciting a port. In this paper an inhomogeneous port boundary conditions will be systematically derived by means of the eigenfunction expansion technique and incorporated into the functional, which will be discretized and solved using the finite element method with high-order interpolatory vector basis functions.