Analysis of Open-Type Waveguides by the Combination of Finite Element Method and Boundary Element Method.

In principle, the finite element method is an analysis method in which an inhomogeneous waveguide with a closed boundary and a complex geometry. By contrast, the boundary element method is suited for the analysis of an open-region problem. In this paper, as a method for analyzing the propagation characteristics of the guided modes in an open waveguide, the finite element method is applied to the electromagnetic field of the interior region while the boundary element method is applied to the field outside the waveguide. The fields of the two regions are then connected at the boundary. By means of the present method, it is possible to analyze without spurious solutions the guided modes in an open waveguide with a cladding made of a different material and an inhomogeneous interior region with a complex geometry. Also, the coefficient matrix of the matrix equation to be solved becomes square. As practical examples, the dispersion characteristics of the rectangular dielectric waveguides and channel waveguides are analyzed so that the validity of the method is verified. [ABSTRACT FROM AUTHOR]