Research and Design of a Dual-Band Reflective Focused Metasurface for Wireless Power Transfer

To solve the problem of single working frequency of traditional reflective focused metasurface, a dual-band reflective focused metasurface is proposed, which can realize independent focusing characteristics at 7.25 GHz and 20.5 GHz. The metasurface unit is composed of metal elements combined by a split-ring resonant structure working at 7.25 GHz and an elliptical resonant structure working at 20.5 GHz in the same plane, dielectric substrate, and ground. Dual-band independent control and 360(?) phase coverage are achieved by adjusting the dimensions of unit. The surface current distribution also verifies the rationality of the designed metasurface element. Based on the principle of quasi-optical path, a dual-band reflective focused metasurface with independent focusing characteristics is designed. Through full-wave simulation, the focusing efficiency at 7.25 GHz and 20.5 GHz is calculated by Poynting theorem, which are 56.9% and 57.5%, respectively. The proposed dual-band metasurface has the characteristics of simple structure and low profile without multi-layer stacking and metal through-holes.