Research on Dispersion Characteristics of TM Modes in Ka Band Square Coaxial Waveguide

In this paper, the characters of electromagnetic field in Ka band square coaxial waveguide (SCW) are analyzed by the finite differential method(FDM), and the dispersion characteristic curves of two lowest TM modes are calculated. Firstly, the cross section of SCW is plotted with square grids. Then the components of the longitudinal field (E_Z) are analyzed and the equations based on FDM are derived. We solve the systems of equations using the software of MATLAB and obtain the results. Finally, the simulation results of HFSS and CST have validated the calculation results.