A decomposition method using FEM for long waveguides

The analysis of an electrically large, perfectly electric conducting (PEC) structure is typically performed using asymptotic electromagnetic formulations, such as, geometric optics (GO), physical optics (PO) and the Uniform Theory of Diffraction (UTD). Due to their less accurate solutions in some problems compared to full-wave techniques, such as, the Method of Moments (MoM) and the Finite Element Method (FEM), full-wave solutions are sometimes preferred, especially, if computational limitations for large problems can be overcome. Therefore, the concept of scatterer decomposition technique for the EM analysis of these structures was introduced by Kinzel [1] more than thirty years ago, and was later expanded to different decomposition methods by many others. These proposed methods were mostly implemented based on the Integral Equation (IE) formulations.