Curve Fitting-Based Phase Optimization for Microwave Power Transfer

Microwave power transfer provides power wirelessly by converting electromagnetic waves emitted by an antenna to DC power using a rectifying antenna (rectenna). We are developing a distributed cooperative power transfer system that intentionally generates constructive interference on a device by applying appropriate phase control to microwaves emitted from each antenna to improve the efficiency of the power supply. This paper proposes a novel phase optimization method to find the optimal phase that maximizes the received power of the device. The proposed method obtains the optimal phase by performing nonlinear curve regression based on the received signal strength indication (RSSI) feedback of the device. Experimental evaluations showed that the proposed method improved the stability of the supplied power and reduced the time of phase optimization in both feedback models.