A Design and Characterization Method of a Scalable Large Transmitting Array for Wireless Power Transfer

This article presents a novel method for designing, characterizing, and calibrating a scalable transmitter with a large number of antenna elements, and for calculating the precise beam collection efficiency (BCE) in radio frequency wireless power transfer (WPT) systems. Rather than simply applying conventional calibration methods from radar systems to WPT systems, this article proposes an efficient calibration technique that reduces calibration time while accurately estimating BCE. The proposed method uses only a single connection at the transmitter array (TXA) input and a fixed reference antenna for WPT calibration, maintaining a simple experimental setup. This approach significantly reduces the time required for calibration and minimizes the space needed. Furthermore, to efficiently distribute RF signals in large array systems while minimizing space requirements, we present a loss compensated series power divider (LCSPD). Our approach is validated using an experimental prototype operating at 5.64 GHz, comprising a 256-element TXA and a 35-element receiver array (RXA). The calibration method’s effectiveness is demonstrated through wireless power transmission experiments employing convex optimized (CVX) patterns at the transmitter. Comparative analysis of simulated and measured received power, using root-mean-squared error (RMSE) and normalized RMSE (NRMSE), shows a high correlation in RXA patterns. In a 0.5-m transmission scenario, we achieved a transmitted power of 6.08 W, received power of 4.37 W, and a BCE of 71.9%, underscoring the potential of near-field focusing in WPT systems and the accuracy of our proposed method.