Electric and magnetic energies within dispersive metamaterial spheres

Exact analytic expressions for the time-averaged electric and magnetic energies within a negative refractive index metamaterial sphere, which is irradiated by a plane wave, are presented. The metamaterial is dispersive and lossy, with both the permittivity and the permeability frequency-dependent and containing damping terms. The frequency dependence of the magnetic and electric energies inside the sphere is obtained, and it is found that the highest energies occur in the frequency range in which the sphere material is left-handed.