Higher order mode analysis of circular coaxial waveguides using finite difference

Abstract

This paper presents a simple technique to evaluate the cut-off wavelengths of circular coaxial waveguides employing the method of finite difference. Curvilinear rectangular meshing has been employed to subdivide the cross-sectional region between the two conductors. Helmholtz equation in polar form is solved with the appropriate boundary condition to evaluate the cut-off wave numbers and correspondingly the cut-off wavelengths for TE and TM modes. Plots of cut-off wavelengths of few modes for various ratios of outer-to-inner radii are depicted.The data obtained from analytical expressions are compared to justify the validity of the analysis.