Broadband Reconfigurable Amplifying Metasurface for Real-Time Wavefront Control

This article presents a broadband reconfigurable amplifying metasurface (BRAM) capable of real-time spatial electromagnetic (EM) wavefront control. The BRAM comprises elements with two patch-patterned metallic layers and a control network layer, which are elaborately optimized to achieve high efficiency and broadband performance. p-i-n diodes and amplifying circuits, serving as tunable components, are integrated into the metastructure for 1-bit nondispersive phase modulation and continuous reflection intensity control, respectively. By individually controlling the bias voltage applied to the amplifier and the p-i-n diodes in the element, a joint control of amplitude and phase with real-time reconfigurability is achieved. A prototype of the BRAM has been designed, fabricated, and measured, demonstrating a peak power amplification of 10.6 dB and an operational bandwidth from 3.15 to 4.92 GHz (relative bandwidth of 43.8%). Various combinations of phase distribution and tunable reflection amplitude are validated to demonstrate the capability of reconfiguring spatial EM wave intensity and scattering pattern across a wide operational bandwidth.