Tunable Cross-Coupled metallic elements loaded epsilon negative and Near-Zero index characteristics based metamaterial

Abstract

This study examines epsilon-negative (ENG) and near-zero index (NZI) tunable cross-coupled (TCC) metamaterial (MTM) unit cells for multi-band wireless communications. The square split ring resonator (SSRR), a cross-coupled metallic element, and a star-like shape are added at the center of the resonator. The EMR value is 10.24, representing the proposed structure's compactness. The tunability characteristics are investigated by varying the cross-coupled nearby metallic element length within the frequencies of 3.38–3.44 GHz, 7.53–8.0 GHz, and 10.24–10.79 GHz. The NZI characteristics are observed within the frequencies of 3.40–4.66 GHz, 7.41–7.75 GHz, and 10.17–10.31 GHz, respectively, while the ENG characteristics are observed at 2.61–5.15 GHz, 6.43–8.23 GHz, and 9.28–10.45 GHz, respectively. The bandwidth of the designed TCC MTM unit cell is 2.49–4.00 GHz, 6.89–7.83 GHz, and 9.75–10.64 GHz, respectively. The tunability, ENG, and NZI characteristics with a high EMR value enable it for critical microwave applications, including S, C, and X frequency bands. The anticipated structure may be a good candidate for enhancing the gain and bandwidth of the antenna and filter designs and operations, as well as frequency stability and efficiency for multi-band wireless communications.