Tunable split ring resonator and its effect

It has been theoretically and experimentally shown that split ring resonators (SRRs) can be used as a negative permeability medium near its magnetic resonance frequency. In this paper, a new structure for magnetic resonance has been designed by introducing a short wire into the common SRRs. The effects of short wire on the transmission characteristics of SRRs and left-handed metamaterials (LHMs) are experimentally and numerically investigated. The results show that an additional capacitor, formed by short wire and the gap side of SRR, leads to higher capacitance around the gap and lower the resonance frequency of SRRs. The resonance frequency of SRRs decreases with the length of short wire, but increases with the distance between short wire and SRRs. The short wire has no significant influence on the negative permeability of SRR. It is also demonstrated that the left-handed transmission peak, negative permeability, antiresonance frequency of permittivity and negative refractive index of LHMs could be tuned by controlling the distance between the short wire and the SRR.