Characterization of the junction between smooth and corrugated circular waveguides

We propose here a rigorous and simplified formulation for the characterization of the junction between a smooth circular waveguide and a periodic corrugated circular waveguide using a hybridization of the mode matching method with the coupled integral equation technique. The modal basis of the Floquet modes, present in the periodic waveguide, is determined basing on the coupled integral equation technique. The results are compared to those obtained by the conventional mode matching method and the agreement is satisfactory. The dispersion diagrams of corrugated circular waveguides are also plotted and the influence of the radius ratio on the apparition of the complex modes is well shown.