Double negative electromagnetic property of granular composite materials in the microwave range

The double negative (DNG) electromagnetic property, i.e. the simultaneous negative permittivity and permeability, of granular composite materials has been studied in the microwave frequency range. The negative permittivity spectrum can be realized by the low frequency plasma oscillation which is generated in the percolated metal particle chain as well as the dielectric resonance of the induced dipole in the isolated metal particle clusters. Meanwhile, the negative permeability spectrum can be obtained by the magnetic resonance of the embedded ferromagnetic particles in the granular composite structure. By combining these negative electromagnetic properties, the DNG characteristics can be produced in the granular composite material. The DNG properties of the Cu/Yttrium Iron Garnet (Cu/YIG) granular composite materials under external magnetic field will be presented; the negative refractive index of the Cu/YIG composite material will also be discussed.