Low-frequency resonances of a chiral sphere filled with a metamaterial

The problem of excitation of a metamaterial sphere by radial magnetic and electric dipoles is considered. The sphere's surface is characterized by the anisotropic conductivity along helical lines. The features of quasi-static resonances of the chiral sphere that are due to the presence of a metamaterial are investigated. It is demonstrated that, depending on the values of the constitutive and geometric parameters of the structure, the resonance fields can be linearly or circularly polarized. Degenerate eigen oscillations are discovered. The fields of these oscillations exhibit different angular dependences in the near and far zones. On the basis of rigorous methods, the frequency characteristics of the structure, as well as the near- and far-field patterns at resonance frequencies, are calculated. An approximate analytical description of quasi-static resonances is proposed.