Dispersion characteristic a periodic substrate integrated waveguide of parallel metallic plates

This paper presents the dispersion characteristic of a substrate integrated waveguide (SIW) of parallel metallic plates. The hybrid generalized scattering matrix and finite-element method (GSM/FEM) method accurately depicting the fields inside the rectangular waveguide section, transitions, and external parallel-plate region. The presented method establishes a rigorous approach to tackle the periodic structure. The dispersion propagation characteristics extracted by the hybrid GSM/FEM method show a region of complex modes between 49 GHz and 52.5GHz. Preliminary study of this complex modes region indicates the mode-coupling of the space harmonics leads to the interesting phenomenon, displaying a null transmission of the SIW TE₁₀ mode. The theoretical three-dimensional electromagnetic field analyses confirmed the null transmission.