Efficient Rectifier for Wireless Power Transmission Systems

This paper describes a full-bridge rectifier and a receiving antenna array for operation within an innovative wireless power transmission (WPT) system. A high-power transmitter using circularly polarized free-space waves and based
on retrodirective antenna array technology, is also employed to boost the overall received RF power at the input of the rectenna. To the authors’ best knowledge, the proposed rectifier circuit and active antenna configuration is the first demonstration of a high power beam tracking system for WPT scenarios, being different from previously reported near-field coupling and other lower power harvesting schemes. The main focus of our present work is the rectifier design, its bench-top measurements, and operation in such a retrodirective, self- tracking microwave system. A novel approach based on in-phase multitone input signals is also developed to improve rectifier efficiency. The rectifier size is 4.5
cm by 2 cm and can offer more than 86% and 75% RF-to-DC rectification efficiency at 27 dBm for an input signal at 1.7 GHz and 2.4 GHz, respectively. This rectifier circuit component can also be employed in other communication applications or WPT systems. For example, to convert to dc received RF signals or power in the radiating near- and far-field in order to wirelessly charge the batteries of home electronics such as smartphones, tablets or IoT devices.