Effect of metal cladding on the modal dispersion characteristic of an annular waveguide with the guiding region section bounded by a square and a circle

Abstract

In this communication we present the modal dispersion curve for four different annular waveguides and on the basis of these dispersion curves we estimate the effect of metal claddings. The inner boundary of the annular cross-section of each waveguide is taken as a square and outer boundary is a circle. The annular cross-section of the guiding region lies between these claddings. One waveguide is made entirely of dielectric material and in the other three, metal loading are used on one or both boundaries. The dispersion curves for some lower modes are presented and compared. The modal cut off values and number of modes at a particular value of V for these waveguides have also been obtained. For this study we use Goell's point matching method. We use the scalar boundary conditions under weak guidance approximation.