Mixed Finite-Element Method for the Closed Waveguide Problem Filled With Anisotropic Media

A mixed finite-element method based on constant transversal and linear normal element and standard linear element, linear transversal and quadratic normal element, and standard quadratic element is used to solve the closed waveguide problem filled with anisotropic media. This numerical method is free of nonphysical modes for solving the closed waveguide problem, which is governed by both electric field and magnetic field. Numerical experiments show that the numerical propagation constants for TEM modes are of high accuracy, and the numerical method given in this paper can support an effective interval for the exact propagation constants of hybrid modes in the waveguide; hence, it is easy to know the numerical accuracy of the approximate propagation constants for the hybrid modes.