An Adaptive Multi-Target Microwave Power Transmission Method Based on Split-Calibration and Power-Focusing Algorithm

Microwave power transmission (MPT) attracts more and more attention in wireless-powered sensor networks (WPSN), due to its ability to power long-range multiple targets rapidly in unmanned factories. However, the necessity for pilot signals in existing MPT systems makes it extremely complex and costly. And it is hard to use in battery-free networks. This paper proposes an adaptive multi-target MPT method by developing a low-complexity Split-Calibration and Power-Focusing (SCPF) algorithm. The algorithm based on power feedback cuts the requirements of pilot signals and Rx channels hardware configuration, and considerably simplifies the system without compromising the transmission performance. Without knowing their locations in advance, the method can adaptively search, activate, and focus the power on multiple battery-free targets. A 5.8GHz prototype is assembled to transmit power to three targets (up to 30.3 dBm (1.07 W) @ 2m) either simultaneously or independently without unfair power distribution.