Artificial dielectric medium possessing simultaneously negative permittivity and magnetic permeability

An artificial dielectric medium comprising two sublattices of spherical particles made of a high-dielectric-constant (high-ε) material, which are embedded into a low-ε dielectric matrix, are considered. Particles belonging to different sublattices have different diameters. It is shown that the properties of this composite structure are equivalent to those of an isotropic medium possessing a negative refractive index (n < 0) in the vicinity of frequencies at which the H ₁₁₁ and E ₁₁₁ oscillation modes exhibit simultaneous resonance in particles of different diameters, which leads to the appearance of electric and magnetic dipole moments, respectively. Averaging of these dipole moments over the volumes of cells formed by the corresponding spherical particles determines their contributions to the permittivity and magnetic permeability of the composite medium. At frequencies above the resonance, both contributions become negative and, hence, the medium exhibits simultaneously negative values of the permittivity and magnetic permeability. The proposed composite structure consists only of dielectric components. Spherical particles with ε _d > 200 can be made of a ferroelectric material.