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.

中文翻译：

---

用于提高未对准无线电力传输效率的可调超材料板

这封信展示了一种可调谐超材料 (MTM) 板，用于未对准条件下的高效无线电力传输 (WPT)，其工作频率为 6.78 MHz，这是 AirFuel 联盟的标准频率。可调谐 MTM 板位于发射器 (Tx) 和接收器 (Rx) 线圈之间，用作可调谐透镜，帮助将磁场聚焦到 Rx 线圈所在的位置。这种可调板由两种类型的晶胞组成，它们可以独立调节以具有适当的负折射率。实验结果表明，可调 MTM 板有效地聚焦磁场，从而即使在未对准的情况下也能提高 WPT 的功率传输效率 (PTE)。