Space Matching for Highly Efficient Microwave Wireless Power Transmission Systems: Theory, Prototype, and Experiments

Microwave wireless power transmission (MWPT) via radio waves has been an important research topic of the WPT systems, where the overall power transfer and conversion efficiency is a key factor to evaluate the system performance. The state-of-the-art work on MWPT has only taken the end-to-end power transfer efficiency in free space or the power conversion efficiency of the receiver (rectenna) into consideration separately when optimizing the power transfer efficiency of the overall system. To comprehensively consider the system-level matching of the entire MWPT system, a novel space matching concept, including aperture field matching, power matching, and impedance matching, is proposed for optimizing the overall power transfer efficiency. By using the space matching method in this work, the optimal designs of the subsystem components such as the transmitting antenna, receiving antenna, and rectifying circuit can be separately obtained to avoid the complex systematic optimization of the large-scale and complicated MWPT system, therefore, significantly improving the overall power transfer efficiency by 19.4% compared with the traditional methods, and reducing the complexity in large-scale system-level design. This work will have valuable implications in the system design of MWPT applications.