Split Ring Resonators With Tapered Strip Width for Wider Bandwidth and Enhanced Resonance

This article presents a modified edge-coupled split ring resonator (SRR). The proposed SRR is composed of two concentric metallic rings with a nonuniform strip width, which is tapered based on the current and voltage profile in the SRR structure. In contrast to other SRR miniaturization methods, which are based on increasing the equivalent capacitance of the SRR, the proposed SRR benefits from both increased capacitance and inductance to preserve the strength and bandwidth of the resonance. It is also shown that compared to a uniform SRR, a tapered SRR with the same electrical size provides a stronger resonance with 84% wider bandwidth, as desired in wideband filter design. The theory and simulation results are validated through measurement.