Modified perfectly matched boundary conditions for open waveguide structures

Proposes a novel idea for the perfectly matched boundary (PMB) to deal with the open region. A similar idea has been proposed by Shen and Macphie [1996] for analyzing a monopole antenna fed by coaxial lines. However their PMB model is not suitable for the eigenvalue problems of open waveguides. To apply the idea of PMB to the eigenvalue problems, we propose a modified PMB by introducing a buffer region, in which the fields satisfying PEC couple with those of PMC fields under a prescribed condition