Metasurface-Enhanced Near-Field Communication Coils

Abstract

Metallic proximity degrades near-field communication (NFC) performance by inducing eddy currents and distorting the coils magnetic field. Conventional NFC systems typically employ ferrite sheets to mitigate these effects. In this work, we propose a thin metasurface composed of an array of capacitor-loaded split-ring resonators tuned to the NFC operating frequency of 13.56 MHz to suppress metal-induced degradation. A printed NFC coil above a metal plate is investigated for three configurations: metal only, metal with ferrite, and metal with the proposed metasurface. Full-wave simulations and measurements demonstrate that the metasurface enhances the magnetic-field intensity and improves coil–metal decoupling. Experimental results show an improvement in transmission coefficient of up to 7.9 dB over an 80 mm transfer distance compared with the metal-only case. Read-range measurements with a commercial NFC reader confirm an increase from 48 mm to 72 mm when the metasurface is used. The proposed approach provides a compact, tunable, and fabrication-friendly alternative to ferrite shielding for metal-tolerant NFC systems, without added bulk or material cost, and avoids the sustainability drawbacks of ferrites.