Dependence of the magnetic-resonance frequency on the cut-wire width of cut-wire pair medium

We investigated some magnetic metamaterials based on cut-wire pairs instead of split-ring resonators to quest for the possibility of a negative magnetic permeability. Several periodic structures of cut-wire pairs were designed and fabricated, and their transmission spectra were measured in the microwave-frequency regime. The width dependence of magnetic-resonance frequency was studied both theoretically and experimentally for the periodic structures of cut-wire pairs. It was found that, besides the length dependence, the magnetic-resonance frequency also depends significantly on the width of cut-wire pair. A simple equivalent-circuit model proposed by Zhou et al. [Opt. Lett. 31, 3620-3622 (2006)] was employed to elucidate this interesting phenomenon and to simulate the width dependence. In the simulation the magnetic and the electric energies of the cut-wire pair were directly calculated to obtain the magnetic-resonance frequency. The theoretical results are in good agreement with the experimental ones. It reveals that there is a rather easy way to manipulate the magnetic-resonance frequency of magnetic-magnetic metamaterials.