Wireless power transfer system prototype with a wide input power range rectifier and power-optimized waveforms

This paper describes a wireless power transfer (WPT) system operating at 2.4 GHz, which is based on waveform optimization technique and a wide input power range rectifier. This latter consists of an RF-to-dc power conversion circuit based on circulators. The waveform optimization is then applied in order to enhance the power conversion efficiency at very low input power levels. The proposed WPT system was prototyped and tested in open and closed loop configurations with different types of obstacles placed between the transmitter and the receiver. The generation of power-optimized waveforms and the control process in the closed loop configuration were carried out using software-defined radio. The obtained experimental results validate the wide input power behavior of the two proposed WPT systems especially when dealing with very low input power levels and relatively dynamic environments. In fact, for the two WPT systems featured a distance of 1 m and a transmitted power of 50mw, dc power levels of about 38 and 11 mu W are harvested in the cases of no obstacle and low attenuation obstacle respectively.