Study of TE and TM modes in waveguides of arbitrary cross-section using an FD-TD formulation

Abstract

The paper describes the application of the finite-difference method in the time domain for obtaining the cutoff frequencies of TE and TM modes in waveguides of arbitrary cross-section. Maxwell's equations are discretised in a two-dimensional space. The application of the discrete Fourier transform also provides the spatial distribution of the modes in the cross-section of the waveguide. The method is validated against rectangular and a circular waveguides, each with a known cutoff spectrum. Finally, the method is applied to determine cutoff wavelengths and modal field distributions in a square coaxial waveguide.