Printed spiral metamaterial resonators for ferrite-less wireless powering system with proximal metal plates

This study proposes the metamaterial-like printed spiral coil (PSC) without using ferrite film to improve the proximity effect of metal plate in wireless power transmission. This four-PSC system is experimentally and theoretically verified by power transmission, impedance matching, resonant frequency, and magnetic field distribution. Results demonstrate that the transmission of the four-PSC system is 10.5 dB higher than the conventional two-PSC system when the backside metal plates are added.