Tunable Single-Negative Metamaterials Based on Microstrip Transmission Line With Varactor Diodes Loading

Abstract—In this paper, tunable single-negative (TSNG) metamate-rials based on microstrip with varactor diodes loading are investigated. By tuning the external voltage, our structure can provide either an epsilon-negative or a mu-negative band gap, with varying gap width (the ratio of bandwidth to center frequency can be from 0 to over 100%) and depth (from 0dB to about −30 dB). Moreover, the tun-neling mode in a heterostructure constructed by epsilon-negative and TSNG metamaterials is also studied. The results show that its trans-mission, Q-factor, and electromagnetic localization can also be con-trolled conveniently. All these properties make our structure promising to be utilized as a practical switching device, or a suitable platform for the study of nonlinear effect in metamaterials. 1.