Design and Validation of a Metallic Reflectarray for Communications at True Terahertz Frequencies

TL;DR

The paper tackles enabling reliable communications in the true terahertz window by using a fixed metallic reflectarray that enforces non-specular reflections at 1–1.05 THz. It presents a patch-based reflectarray with fixed delay stubs, integrated on a Si/SiO2 substrate, and validated through terahertz-time-domain spectroscopy and a CW THz testbed, including data-carrying signals. The results show selective non-specular steering to ~30 degrees, a resonance near 0.9–1 THz with fabrication-tolerance-induced shift, and broadband demonstrations (5-tone and 500 Mbps QPSK) confirming practical THz links. The work demonstrates a practical step toward robust, high-rate THz links and highlights future tunability and bandwidth scaling.

Abstract

Wireless communications in the terahertz band (0.1-10 THz) is a promising and key wireless technology enabling ultra-high data rate communication over multi-gigahertz-wide bandwidths, thus fulfilling the demand for denser networks. The complex propagation environment at such high frequencies introduces several challenges, such as high spreading and molecular absorption losses. As such, intelligent reflecting surfaces have been proposed as a promising solution to enable communication in the presence of blockage or to aid a resource-limited quasi-omnidirectional transmitter direct its radiated power. In this paper, we present a metallic reflectarray design achieving controlled non-specular reflection at true terahertz frequencies (i.e., 1-1.05 THz). We conduct extensive experiments to further characterize and validate its working principle using terahertz time-domain spectroscopy and demonstrate its effectiveness with information-carrying signals using a continuous-wave terahertz testbed. Our results show that the reflectarray can help facilitate robust communication links over non-specular paths and improve the reliability of terahertz communications, thereby unleashing the true potential of the terahertz band.

Figures (7)

• Figure 1: Schematic and optical images of the reflectarray. The size of the patterned area in (c) is 12.75 $\times$ 12.75mm.
• Figure 2: Schematic of the measurement setup in reflection geometry.
• Figure 3: reflectance measurements of the reflectarray normalized to the substrate.
• Figure 4: A block diagram depicting the interconnection between the various transmitter and receiver components of the TeraNova testbed.
• Figure 5: Experimental validation setup of the fabricated metallic reflectarray using the 11.05 up and downconverter frontends depicting a controlled reflection scenario at $\theta=\ang{30}$.