Exact radiation from an axial dipole antenna on a prolate metallic spheroid coated with layers of isorefractive and anti-isorefractive materials

The geometry analyzed in this paper consists of a metallic prolate spheroid coated with confocal spheroidal layers of lossless materials whose refractive indexes are either equal (isorefractive) or opposite in sign (anti-isorefractive) to the refractive index of the medium surrounding the structure. The primary source is an electric dipole located on the axis of symmetry and axially oriented. The fields in the various regions are written as infinite series of products of radial and angular prolate spheroidal functions, and the modal expansion coefficients are determined exactly by imposing the boundary conditions, thus yielding a new canonical solution to a radiation problem. Numerical results are presented and discussed.