Spheroidal vector wave eigenfunction expansion of dyadic Green's functions for a dielectric spheroid

The dyadic Green's functions for defining the electromagnetic (EM) fields for the inner and outer regions of a dielectric spheroid are formulated. The dyadic Green's function for an unbounded medium is expanded in terms of the spheroidal vector wave functions and the singularity at source points is extracted. The principle of scattering superposition is then applied into the analysis to obtain the scattering spheroidal dyadic Green's functions due to the existing interface. Coupled equation systems satisfied by scattering (i.e., reflection and transmission) coefficients of the dyadic Green's functions are obtained so that these coefficients can be uniquely solved for. The characteristics of the spheroidal dyadic Green's functions as compared with the spherical and cylindrical Green's dyadics are described and the improper developments of the spheroidal dyadic Green's function for the outer region of a conducting spheroid in the existing work are pointed out.