Load Design and Waveform Optimization for Near-Field Wireless Powered Communications Using a Coil Array

Wireless powered communication networks (WPCNs) are a promising option for remote powering of Internet of Things (IoT) devices. Most research is focussed on remote powering with multiple antennas over the far field. This communication considers near-field WPCNs over inductively coupled circuits consisting of an access point (AP) with a coil array and a single-coil transponder. The advantages of inductive coupling include high power transfer efficiency, robustness to near-field obstructions, and relatively simple uplink communications via load modulation. The WPCN is modeled using scattering parameters in this communication, and the optimal transmit signal and load impedance are derived. A novel technique to estimate the unknown scattering parameters is also proposed.