Left-Handed Characteristics Tunable C-Shaped Varactor Loaded Textile Metamaterial for Microwave Applications

This paper presents a textile-based C-shaped split-ring resonators (SRR) metamaterial (MTM) unit cells with an electrical tunability function. The proposed MTM was composed of two symmetrical C-shaped SRR combined with a central diagonal metal bar, whereas the RF varactor diode is placed on the backside of the splitted ground plane. Stopband behavior of single and array MTM unit cells were analyzed while the achieved negative index physical characteristics were widely studies. Though four different MTM arrays (i.e., 1 × 1, 1 × 2, 2 × 1, and 2 × 2) were analyzed in simulation, a 2 × 2-unit cell array was chosen to fabricate, and it was further undergone experimental validation. This proposed tunable MTM exhibits double negative (DNG)/left-handed properties with an average bandwidth of more than 2.8 GHz. Furthermore, attainable negative permittivity and negative permeability are within 2.66 to 9.59 GHz and within 2.77 to 15 GHz, respectively, at the frequency of interest (between 1 and 15 GHz). Moreover, the proposed tunable MTM also showed tunable transmission coefficient characteristics. The proposed electrically tunable textile MTM might function in a dynamic mode, making it suitable for a variety of microwave-wearable applications. A satisfactory agreement between simulations and experiments were achieved, demonstrating that the proposed MTM can operate over a wide bandwidth.