Wideband Stacked Metamaterial for a Compact and Efficient Dual-Band Wireless Power Transfer

A novel wideband stacked metamaterial is proposed for a dual-band wireless power transfer (WPT) system. Firstly, two types of split-ring resonators (SRRs) of different self-resonance frequencies are proposed. Then we sandwiched each type of the unit cell. Consequently, the proposed metamaterial exhibits wideband near-zero characteristics on both the real part and imaginary part of the permeability. Also, compared with conventional 1-D metamaterial [2], the proposed metamaterial can significantly empower both bands simultaneously of the dual-band WPT system. An experiment shows that the proposed metamaterial of size (20 mm × 20 mm 5.468 mm) has improved the efficiencies of both bands from 18.6%, 22.9% to 51.8% and 47.8%, respectively, at a wireless power transfer distance of 20 mm.