Multitarget Wireless Power Transfer System Using Metasurface for Quasi-Bessel Beams With Large Half Power Beam Length

We propose a multitarget wireless power transfer (WPT) system using a transmissive metasurface with quasi-nondiffraction Bessel beams. To provide similar powers for more different targets, a special metasurface is designed to achieve uniform energy distributions in the nondiffraction area of Bessel beams, which can increase the half-power beam length (HPBL) by 10% compared with ordinary Bessel beams. A transmissive metasurface unit with transmission coefficient of more than 90% and a phase shift range greater than 360° are presented to form the metasurface at 10 GHz, which further ensures the high efficiency of the generated Bessel beams. Various receiving parameters are analyzed at the energy receiving end to reduce the influence between different targets. Receiving antennas that can harvest energy are designed with different apertures at 10 GHz, and the system efficiencies with different receiving apertures and different spaces between the receiving targets are analyzed to determine the appropriate receiving parameters. Finally, a multitarget metasurface WPT system based on the quasi-Bessel beams is fabricated. Simulation and experimental results show that the system can achieve almost equal WPT efficiency for five targets. More than 91% of the incident power can be modulated to form the quasi-Bessel beams, and the efficiency of each target is greater than 4.4% for the simulated results and greater than 3.3% for the measured results. Analysis of the designed rectifier circuit further proves the rationality of the proposed WPT system, which can be used for multiple charging targets and maintain a uniform power transfer efficiency. The quasi-Bessel beams achieve the high-efficiency multitarget WPTs and simplify the circuit design of receiving targets, making WPT applicable to more scenarios.