Beam-steering transmitarray with active frequency selective surface for wireless power transmission

This letter presents a beam-steering antenna with an active frequency selective surface (AFSS). The proposed AFSS-based antenna consists of a source antenna and an active frequency selective surface as a superstrate. The AFSS unit consists of three layers, where the upper and lower layers are identical and the middle layer has a slight variation. This structure makes it possible to obtain 360 degrees phase variation, which can be achieved by changing the bias voltage at both ends of the varactor diodes in the case of three layers. Its passband is about 40 MHz (from 5.14 to 5.18 GHz). Finally, the proposed unit cell was stacked into a 5 x 5 array; both simulated and measured results demonstrated that the transmitarray has the scan ability of +/- 25 degrees at 5.16 GHz. The proposed transmitarray is suitable for dynamic wireless power transmission.