A Retro-Reflective Beamforming Scheme based on Heterodyne Technique for Wireless Power Transmission

A retro-reflective beamforming scheme based on the heterodyne technique is experimentally demonstrated for wireless power transmission applications. Compared with the conventional heterodyne scheme, the wireless power transmitter does not include any local oscillators. It receives 2.9-GHz pilot signal broadcasted by a wireless power receiver, employs a frequency doubler to obtain the second harmonic signal at 5.8 GHz, and subsequently uses the 5.8-GHz signal to achieve phase conjugation. Experimental results clearly indicate that the proposed scheme is able to deliver directive wireless power beam to the wireless power receiver in reaction to the pilot signal.