Design, Measurement and Analysis of Near-Field Focusing Reflective Metasurface for Dual-Polarization and Multi-Focus Wireless Power Transfer

A new design of dual-polarization and multi-focus near-field focusing (NFF) reflective metasurface for wireless power transfer (WPT) system is proposed in this paper. In terms of multi-beam phase synthesis of reflective metasurface, the dual-polarization metasurface with independent regulation characteristics is introduced to realize multi-focus and high-efficiency WPT. The single-feed single-focus and the single-feed dual-focus metasurface working at X-band (10 GHz) with 26 × 26 elements in two polarizations are designed, fabricated and measured by planar near-field scanning experiments. Furthermore, a compact antenna is designed and fabricated as the receiver to form a practical WPT system. The measurement results show that a NFF transfer system is 15 dB higher than a non-NFF transfer system. Through full-wave simulation and experiments of three cases, single focus, dual-focus, and single focus with dual-polarization can respectively realize the maximum focusing efficiency of 71.6%, 68.3% and 65.9%. The relative bandwidth with 50% power focusing efficiency of these three cases are all about 12%, which demonstrates the stability and feasibility of the NFF reflective metasurface for practical WPT applications.