A Wideband and Reconfigurable Near-Field Focusing Metasurface for Microwave Wireless Power Transfer Systems

This letter proposes a wideband and reconfigurable metasurface (MS) that can be used for the dynamic adjustment of the near-field focal position. The MS element is a Fabry-Perot-like cavity, composed of a three-layer structure. One-bit phase quantization can be achieved by changing the ON or OFF states of the two positive-intrinsic-negative(p-i-n) diodes in the MS element respectively. The MS is composed of 10×10 elements, which is simulated, fabricated and measured. The insertion loss is less than 1 dB in 4.6-6.1 GHz and the phase difference of the transmitted waves passing through the MS elements in the two states is 180°. The simulated and measured results indicate that when the horn antenna is used as the feed source to illuminate the MS, the MS can achieve reconfigurable near field focusing. Moreover, the adjustable range of the focal point is 140mm×140mm×120mm. The maximum transmission efficiency and focusing efficiency are 77.83% and 43.3%, respectively.