FSS-inspired transmitarray for dynamic beamforming and gain control

In this paper, we propose a concept of combining the methodology of phase coding modulation with frequency selective surface (FSS) inspired transmitarray (TA) to achieve the ability of dynamical beamforming and gain control in microwave regime. The TA element composed of five-layer stacked bandpass FSS units separated by small air gaps. Each FSS unit comprises a metallic octagon slot with a pair of varactor diodes loaded along the polarization direction. The elaborately designed feeding network makes it possible to modulate the transmission phase of each element. Different phase coding sequences are performed through changing the bias voltage configurations, then the radiation far field of the proposed TA can be tailored in real time. Dynamic beamforming and gain control under different encoding arrangements are exhibited to demonstrate the physical mechanism of electromagnetic (EM) manipulation with this method. The proposed strategy is verified by numerical simulations and experiment. This work adds new function for TA and can reshape its application prospect, such as reconfigurable beam emitter for multilink data transmission, long range point-to-point (PTP) wireless links and radio frequency energy harvesting.