Abstract: The equivalent permittivity and permeability of metamaterials can be generated by the interaction of electromagnetic waves with specific metal structured cell array. Using the unified description of the interaction by RLC series resonant circuit, we conclude that both the real part of the equivalent permittivity and permeability are negative when the incident wave frequency is greater but close to the resonant frequency; and the imaginary parts of them are positive in any case.

Key words: magnetic media, negative permeability, equivalent circuit, electric resonance, magnetic resonance