Ferro-nano-carbon split ring resonators a bianisotropic metamaterial in X-band: Constitutive parameters analysis

Abstract

We report on preparation and evaluation of constitutive parameters for ferro-nano-carbon (FNC) split ring resonators (SRRs) behaving as a bianisotropic left-handed material (LHM) that generated an electromagnetic cloak in sub-X-band region (8.5–10 GHz). Initially, FNC was synthesis by pyrolysis of 1,7,7-trimethyl-bicycloheptan incorporated with variable wt % (3–20) of cobalt. Morphological studies showed spherically concentric shells (40–50 nm) of FNC interconnected spatially. In Raman, FNC vibration modes indicated encaging of Co-sp3 phase within sp2 shells, whereas, dielectric studies revealed low-frequency orientational polarization attributed to chair-to-chair sp2 segmental motion surrounding Co-sp3 fraction. In VSM, higher exchange anisotropy emerged in FNC due to randomly spaced, smaller concentration of Co-structural inhomogeneities interacted, indirectly, within carbon super-lattice. The FNCs were implemented into SRRs to investigate microwave scattering response, experimentally. The constitutive parameters were extracted and, comparatively, studied using Nicolson-Ross-Weir and retrieval technique. Analysis of obtained results is presented. Scattering (S)-parameters and fields were simulated, indicating S11 around - 20 and S21 ∼ 0 dB, at 8.5 GHz with concealing of incident field at SRRs cell. The resemblance of simulated S-parameters with experimental values is discussed. Broadly, out of phase response of Co-sp3 dipolar fields segregated charges in opposite direction to harmonically oscillating incident magnetic field. This resulted into bianisotropic LHM behavior of FNC when transformed into SRRs; generating a cloak like response, particularly, at 8.5–10 GHz.