Electromagnetic resonances of immersed dielectric spheres

The complex natural resonances (CNR) for lossless dielectric spheres in a lossless dielectric medium are investigated. Significant differences between the external and internal resonances are presented. The external resonances are related to the external creeping waves and the internal resonances to the internally reflected waves. The internal resonances are more important in practice because of their smaller damping factors. Simple physical interpretation for predicting the resonance behavior of a general dielectric sphere is obtained.