A Near-Field Communication Coil Integrated with a Metasurface

This paper presents a novel approach for mitigating the undesirable effects of metallic interference in near-field communication (NFC) and wireless power transfer (WPT) systems. Conventional methods rely on ferrite layers to shield the coil from eddy currents induced by nearby metallic structures. However, ferrite layers are often bulky, rigid, and expensive, limiting their applicability in modern compact and flexible systems. Furthermore, ferrites are also rare materials and are thus not sustainable. To address these challenges, we introduce a metasurface-based structure utilizing split-ring resonators (SRRs), integrated with capacitances to achieve resonance at 13.56 MHz. The metasurface is positioned between the coil antenna and the metallic surface. Comparative analysis of three configurations - coil above metal, coil with ferrite shielding, and coil with metasurface - demonstrates the exceptional performance of the metasurface. The results show that the metasurface effectively suppresses eddy currents and amplifies the magnetic field intensity through resonance. This study highlights the potential of metasurfaces as efficient, flexible, and cost-effective alternatives for enhancing NFC and WPT systems in metallic environments.