Tunable Metamaterial Slab for Efficiency Improvement in Misaligned Wireless Power Transfer

This letter presents a tunable metamaterial (MTM) slab for high-efficiency wireless power transfer (WPT) in misaligned conditions, which operates at 6.78 MHz, an AirFuel Alliance Standard frequency. The tunable MTM slab is located between transmitter (Tx) and receiver (Rx) coils serving as a tunable lens to help focus the magnetic field toward the place where the Rx coil is located. This tunable slab consists of two types of unit cells which can be independently tuned to have proper negative refractive indices. The experimental results show that the tunable MTM slab effectively focuses magnetic fields, thereby improving the power transfer efficiency (PTE) of WPT even in a misaligned condition.