Suppression of the slot-mode propagation in a slitted waveguide

Periodic transverse slots are introduced to a slitted waveguide for the purpose of suppressing slot-mode propagation. The effect of the transverse slots on the perturbed TE₁₀ mode are investigated using the finite-difference time domain (FDTD) method and periodic boundary conditions. Simulation results for two designs are presented and compared with analytical results. The first design suppresses the slot-mode propagation over a large portion of the X-band bandwidth. The second design uses minimal perturbation to suppress the slot-mode radiation while minimizing the impact on the propagation characteristics of the perturbed TE₁₀ mode. It will be shown that designs with wideband and narrowband suppression of the slot-mode are possible. However, it will be seen that the wider band the suppresion, the larger the perturbed TE₁₀ mode wavenumber deviates from the slitted results.