Wave Propagation in Composites of Plasma and Metamaterials with Negative Permittivity and Permeability

Wave propagation is observed through a negative permeability metamaterial immersed in gaseous plasma. A 3D array of split ring resonators (SRR) is enveloped by an inductively heated argon plasma with a nominal plasma frequency of 2.65 GHz. Transmission spectra show electromagnetic waves traverse the composite medium from 1.3–1.7 GHz for which the permeability of the SRRs and the permittivity of the plasma are simultaneously negative. Only surface waves and evanescence are observed outside this frequency band. The edge of the transmission band also shows negative group velocity, albeit with high wave attenuation. The free electron density of the plasma is coupled to the inductive heating, allowing dynamic reconfiguration of the metamaterial’s frequency band and wave impedance.