Mode Analysis of the Corrugated Substrate Integrated Waveguide

The corrugated substrate integrated waveguide (CSIW) is compatible with substrate integrated waveguides (SIWs) but permits ease of integration of active devices. The CSIW differs from the SIW by using quarter-wave open-circuit stubs in place of vias to form the electric sidewalls. In this paper, an efficient analysis method has been formulated that distributes the loading effect of each stub across its width. The formulation was used to calculate CSIW dispersion characteristics and identify mode behavior in the vicinity of the desired TE10 mode. Simulations and measurements of X-band CSIWs were used to validate the calculations. Apart from normal waveguide mode behavior, surface wave-like behavior was also identified.