Design and analysis of a compact multi-band flexible metasurface with low-loss characteristics for S, C, and X-band applications

Abstract

Abstract In this study, the focus is on developing a compact, multi-band, and flexible metasurface (MS) with low-loss characteristics for microwave applications. Recently, there has been a strong need to explore MS designs that can efficiently operate across multiple resonance bands while maintaining a compact size and low loss for advanced performance in ever-increasing microwave technology. The unit cell configuration of the MS is designed using three split-ring resonators (SRRs) interconnected with a spiral notch to achieve multi-resonance characteristics with low loss. The miniaturization of the proposed MS is achieved through inductive loading, which is enabled by extending the metallic strip length within the unit cell. Increasing the metal length increases the effective inductance-to-capacitance ratio (L/C), resulting not only in greater compactness but also lower loss. Despite its compact size and low loss, the numerical simulation results reveal that the proposed SRR-MS unit cell exhibits hexa-resonance frequencies at 2.7 GHz (S-band), 4.22 GHz, 6.25 GHz (C-band), 8.27 GHz, 9.65 GHz, and 10.95 GHz (X-band), respectively. The proposed MS exhibits six distinct $$\epsilon$$ -negative (ENG) regions and one $$\mu$$ -negative (MNG) region across the S, C, and X microwave frequency bands with high refractive index (HRI) properties near all six resonances. Importantly, the low-loss behavior is maintained across all six resonance frequencies of the MS. Additionally, the MS is designed on a single-sided flexible dielectric substrate, and its performance characteristics remain stable to some extent under bending and twisting.