Dispersion Characteristic of Elliptical Waveguide Under New Boundary Condition

A special type of elliptical waveguide with sheath helix on its core and cladding boundary is proposed and investigated analytically. In this case we are using the reverse boundary condition of the helix which is different from normal boundary condition. Using elliptical coordinate (ξ, η, z) system, field components are obtained for even and odd modes. The present paper is concentrated on even modes only. The Eigen value equation for the proposed waveguide is studied by solving the (4 × 4)matrix. The Eigen value equation obtained contains the Mathieu and modified Mathieu functions. Applying approximations these functions convert into the form of Bessel and modified Bessel functions. The Eigen value equation obtained in this paper is the starting point for further analyses of modes behavior through dispersion curves under new boundary conditions.