Coupling of Modes on a Tapered Dielectric Cylinder

A generalized coupled-mode formulation is presented for propagation in nonuniform media, where the modes are those associated with both the discrete and continuous eigenvalue spectrum. The theory includes metallic and dielectric waveguide non-uniformities as special limiting cases. Analytic results are presented for a multimode linear tapered dielectric cylinder excited by the HE₁₁ mode.