Cylindrical coordinate system-based FDTD method for analysis of THz circular waveguide coated by dielectric material

This paper presents the analysis of reflectivity and transmissivity for terahertz (THz) circular waveguide coated by dielectric material using cylindrical coordinate system-based finite difference time domain (FDTD) method. The analysis is conducted by discretizing a model of THz circular waveguide with the radius of 50μm and the length of 250μm. The scattering parameters in term of reflectivity and transmissivity are extracted from the electric fields obtained at different observation planes. Some scenarios in the analysis of reflectivity and transmissivity are applied by varying the thickness of coated dielectric material inside the circular waveguide compared to the hollow circular waveguide. Others scenarios are carried out by introducing some values of conductivity into the dielectric material. From the results, it is shown that resonant frequencies of circular waveguide coated by dielectric material in transverse electric (TE) mode are lower than the hollow waveguide. It also shows that the circular waveguide coated by dielectric material with the thickness of 7.5μm and the conductivity of 250S/m has better transmissivity than the hollow circular waveguide.