Multi-band planar miniaturised negative-index metamaterials

In this paper, a miniaturised negative-index metamaterial (NIM) based on planar concentric split ring resonators was designed, simulated, fabricated and tested that can maintain NIM properties. The offered metamaterial structure showed miniaturisation factor compared with traditional metamaterial unit cells and conformed better effective medium ratio (EMR). Finite-difference time-domain method-based computer simulation technology for the numerical analyses and a vector network analyser (N5227A) was used for the measurements. The proposed metamaterial exhibited multi-band response in conjunction with the NIM property over the certain frequency bands in the microwave spectra and the EMR considerably improved compared to previously reported metamaterials. The measured results revealed good agreement with the simulated results. The distribution of surface current, electric field and equivalent circuit model were verified for the proposed structure. The size, scattering parameters and EMR parameters of the proposed miniaturised NIM is appropriate for multi-band applications.