High Efficiency Metamaterial-based Multi-scale Wireless Power Transfer for Smart Home Applications

This paper presents a high efficiency multi-scale wireless power transfer(MSWPT) system using a metamaterial(MTM) slab, which operates at 6.78MHz(AirFuel Alliance standard) for near-field WPT and 433MHz(ISM band for smart home devices) for far-field WPT. The MSWPT system is configured to have the power transfer efficiency(PTE) greatly enhanced with the MTM slab which has an electromagnetic wave focusing capability for both frequency bands. A prototype of the MSWPT system is designed, fabricated, and characterized. The PTE of the fabricated MSWPT at a distance of 50cm is increased from 5.42% to 50.12% with MTM slabs at 6.78 MHz, i.e. 9.25 times enhancement while the PTE at a distance of 2.5m is increased from 0.72% to 3% with MTM slabs at 433 MHz, i.e. 4.17 times enhancement. It is concluded that the transition from 6.78MHz near-field WPT to 433MHz far-field WPT is advantageous in MSWPT when the distance is greater than 90cm.