Design and Implementation of 5.8 GHz RF Wireless Power Transfer System
Je Hyeon Park, Nguyen Minh Tran, Sa Il Hwang, Dong In Kim, Kae Won Choi
Abstract
In this paper, we present a 5.8 GHz radio-frequency (RF) wireless power transfer (WPT) system that consists of 64 transmit antennas and 16 receive antennas. Unlike the inductive or resonant coupling-based near-field WPT, RF WPT has a great advantage in powering low-power internet of things (IoT) devices with its capability of long-range wireless power transfer. We also propose a beam scanning algorithm that can effectively transfer the power no matter whether the receiver is located in the radiative near-field zone or far-field zone. The proposed beam scanning algorithm is verified with a real-life WPT testbed implemented by ourselves. By experiments, we confirm that the implemented 5.8 GHz RF WPT system is able to transfer 3.67 mW at a distance of 25 meters with the proposed beam scanning algorithm. Moreover, with the proposed beam scanning algorithm, the power transfer efficiency reaches 20.32 % and 0.24 % at distances of 0.5 and 5 meters, respectively, whereas the far-field-only-scanning scheme achieved the transfer efficiencies of 13.45 % and 0.23 % at the same receiver positions. Since the proposed transmit antenna array has the maximum linear dimension of 299.12 mm, the approximate boundary between far-field and radiative near-field is 3.45 meters based on the Fraunhofer distance calculation. The results show that the proposed algorithm can effectively cover radiative near-field region differently from the conventional scanning schemes which are designed under the assumption of the far-field WPT.