Monolithic GaAs Transmitarray With Amplitude Reconfigurability for 2-D Terahertz Beam Steering

Terahertz (THz) large-scale phased arrays for sixth-generation (6G) communication face integration challenges with T/R modules due to their millimeter-scale dimensions. While reconfigurable transmitarrays (RTAs) enable scalable implementations without bulky feed networks, most reported designs are limited to 1-D steering or rely on complex structures that pose challenges for monolithic fabrication. As a solution, we propose and implement a 210–220-GHz amplitude-RTA (ARTA) system. The ARTA features a single-layer, via-free chip design, with a Schottky barrier diode (SBD) monolithically integrated on each element, enabling element-wise reconfigurability of transmittance to incident waves while reducing fabrication cost and complexity. Meanwhile, an optimal 1-bit amplitude modulation strategy for ARTA beam steering is developed with maximized modulation efficiency. A <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.7\times 5.7$</tex-math> </inline-formula>-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $</tex-math> </inline-formula> ARTA chip, consisting of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$20\times 20$</tex-math> </inline-formula> elements, was fabricated on a gallium arsenide (GaAs) wafer. Based on this chip, a compact, portable <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$20\times 20$</tex-math> </inline-formula> ARTA system was implemented by integrating dedicated beam-control circuits and a THz RF chain, enabling high-speed THz communication with real-time 2-D beam steering. Numerical and experimental results validate that, with the proposed modulation strategy, the ARTA system can steer beams over ±30° in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i>-plane and from −30° to 20° in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i>-plane, demonstrating potential for high-speed beam steering, such as multinode communication in satellite networks.