Three-dimensional double-negative metamaterials resonating at 13.5 GHz

A three-dimensional double-negative (DNG, epsiv < 0, mu < 0) metamaterial has been designed to operate near 13.5 GHz. The metamaterial was comprised of patterned copper split ring resonators (SRRs) and wires on a Rogers 5880 substrate. The SRRs and wires were each constructed in three orthogonal planes to give a near-isotropic response to an arbitrarily polarised EM excitation. As this material responds to radiation of arbitrary polarisation and direction, it is referred to as a 3E3H structure where all the six components of the EM tensor are present. The simulated losses in the unit cell are large (2 dB/cm), a major contribution being ohmic effects in the SRRs. For many applications, unit cells of lower dimensionality, that is, 2E2H or 1E1H, where only a restricted number of the elements of the EM tensor are needed, can perform nearly as well as 3D DNG materials, but with much lower loss, and thus may be preferred as an alternative to an isotropic 3E3H structure.