A novel volumetric folded ring resonator metamaterial structure

A novel folded ring resonator (FRR) is shown to deliver an equivalent bandgap response to a planar square closed ring resonator (CRR). In addition to being significantly more compact in two dimensions, the folded ring resonator is polarization independent. The bulk behavior of a cubic lattice of the novel structure demonstrates backward mode behavior centered at 4.5 GHz with a bandwidth of 12.2% as derived from the dispersion curve. Parametric sweeps of the critical dimensions are presented showing the tunability of the structure. The field nature of the backward mode is explained in terms of the realized negative permittivity and permeability. For finite thickness slabs of the novel substrate, the material parameters and phase are shown to indicate the presence of a backward mode in agreement with the bulk response.