Resonant frequency computation of dielectric material loaded circular waveguide using cylindrical coordinate system-based FDTD method

Abstract

In this paper, a cylindrical coordinate system-based finite difference time domain (FDTD) method is proposed for resonant frequency computation of dielectric material loaded circular waveguide. The computation is carried out by discretizing a model of circular waveguide resonator which has the radius of 10.12mm and the length of 60mm using FDTD notation and numerically computed to determine its resonant frequency in transverse electric (TE) mode. Some scenarios are applied for loading the waveguide by dielectric materials to analyze its resonant frequency to be compared with the hollow circular waveguide. From the results, it is shown that the TE mode resonant frequency for loaded circular waveguide is lower than of hollow circular waveguide which satisfies the numerical prediction. Meanwhile, from the scenario of circular waveguide partially loaded with dielectric material which is coated from outer region in a certain depth, it is found that the resonant frequency varies depending on the depth of dielectric material or on the volume proportion of dielectric material in the waveguide. The result shows when the proportion of dielectric material is 36% the lower resonant frequency is similar with the waveguide fully loaded with dielectric material.