Metamaterial Adaptive Frequency Switch Rectifier Circuit for Wireless Power Transfer System

In this article, a novel metamaterial adaptive frequency switch (MAFS) rectifier circuit is proposed to expand the operating frequency range of the rectifier circuits for wireless power transfer (WPT) systems. Due to the nonlinearity and complex input impedance of the rectifying circuit, the MAFS technology is introduced to improve the matching performance of the rectifier circuit working in different bands. We can use MAFS technology to achieve independent regulation of a single rectifier circuit at different bands, simplifying the rectifier's topology and complexity. A dual-band rectifier circuit and a broadband rectifier circuit are designed to verify the feasibility of the structure. The experimental results show that the designed dual-band rectifier circuit has high conversion efficiency (more than 50%) in two broadbands, 3.2–3.6 and 5.2–6.2 GHz, for 5G and Wi-Fi bands. In addition, the conversion efficiency of the designed broadband rectifier circuit from 4.7 to 6.2 GHz is higher than 50% at 13 dBm. The fractional bandwidth is expanded by 10% compared with the multiplexed rectifier circuit structure. Therefore, the proposed rectifier circuit structure can significantly broaden the operating frequency range and has a simple design, which can be widely used in a WPT system.