Theoretical Analysis of Retro-reflective Beamforming Schemes for Wireless Power Transmission to Multiple Mobile Targets

In this paper, several retro-reflective beamforming schemes for wireless power transmission to multiple targets (with “targets” standing for “wireless power receivers” in this paper) are analyzed with the aid of numerical simulations. Various practical complications are identified if the pilot signals of multiple targets are not differentiated from each other properly. A retro-reflective beamforming scheme based on frequency division, in which multiple targets transmit continuous-wave pilot signals at respective frequencies, is demonstrated capable of generating multiple wireless power beams aiming at the targets respectively with power transmission performance in excellent agreement with the theoretical values.