Multi-Posture Microwave Power Transmission with Dual Alignment of Transmitting and Receiving Beams by Forward and Backward Time Reversal

In actual microwave power transmission (MPT) scenarios such as smart factory, the system efficiency and output dc power will decrease when the receiving antenna array of the multi-posture receiver does not face the transmitting antenna. To address the challenge of efficiently transmitting energy from the transmitter to a multi-posture receiver, a multi-posture MPT scheme based on forward and backward time reversal (TR) is proposed. This letter introduces phase shifters in the multi-posture receiver, enabling the beam of receiver to have steering capabilities. Importantly, inspired by the adaptive beam alignment characteristic of TR, the phase shifters of receiver are configured to align the beam of the offset receiver with the transmitter using the backward TR method, while the phase shifters of transmitter are configured to align the beam of the transmitter with the receiver using the forward TR method. So, dual alignment of the transmitting and receiving beams is achieved. A prototype of the multi-posture MPT system is established. The experiment results show that the output dc power of the multi-posture MPT scheme is 30.6 dB higher than the traditional MPT scheme when the multi-posture receiver changes its orientation, demonstrating the effectiveness of the multi-posture MPT scheme.