Design of Near-field Focused Metasurface for Wireless Power Transfer

In this paper, a near-field focusing "embedded star" reflection metasurface structure for wireless power transmission is proposed. The structure consists of 28×28 reflection units with a size of 364 mm×364 mm and an operating frequency of 5.8 GHz. The structure proposed in this paper has a more compact size and achieves more precise phase compensation, thus further improving the electromagnetic near-field focusing performance and improving the efficiency of medium-long distance wireless power transmission. In addition, the designed metasurface element structure is center symmetric and polarization insensitive. The results of simulation analysis and experimental testing show that the designed metasurface has a compensation phase range of 360° in the 5.8 GHz~12 GHz band. At 5.8 GHz, the flatness of phase compensation curve is 0.972 4. Under horizontal polarization and vertical polarization incidence, the power transfer efficiency of metasurface to focal observation plane is 72.6% and 73.3%, respectively. The simulation results are in good agreement with the experimental results.