Investigation of dielectric-loaded hard-walled rectangular waveguides using a numerical spectral domain technique

The GIDMULT algorithm (Z. Sipus et al, Appl. Comp. EM Soc. Journ., vol.13, no.3, p.243-254, 1998.) was used to investigate rectangular waveguide structures with finiteness in both transverse coordinates. Conventionally, the approach is unable to treat the finiteness of the side walls. This is circumvented by predefining the phase constant along the finite coordinate defining the walls, and then performing a numerical search for the modal propagation constant associated with field maxima. The particular rectangular waveguide configuration studied in this work was the dielectric-loaded hard E-plane walled rectangular waveguide. The GIDMULT-generated solutions agree well with those obtained analytically, validating this method and its flexibility. This technique was also used to study how the transverse field distribution over the guide cross-section varies with deviation of operating frequency from the TEM frequency. It was observed that the TEM frequency serves as a cutoff for surface waves along the dielectric slab.