Near field wireless power transfer and quadrature amplitude modulated (QAM) communication link

Abstract

We present a near field wireless power transfer (NF-WPT) link which is also capable of data communication through complex, quadrature amplitude (QAM) load modulation. We present a method for designing a 4QAM constellation that allows for minimal degradation of the NF-WPT link efficiency by minimizing the complex reflection coefficient. Using a modulation board and a resonant 4-coil NF-WPT system we demonstrate 307.2kbps data transmission, representing a 12.7% fractional bandwidth, over a distance of 1-coil diameter (29cm) at a carrier frequency of 2.428MHz. Efficiency of the NF-WPT is only reduced from 68% to approximately 63.1% when used for data communication as well as power transfer.