Subterahertz circularly polarized 1k-pixel reflective surface for 6G applications

Wireless communication is a hot topic of research and development at this moment. The need of increasing data transfer rates and connection stability within vast digitalization of people interactions sets new tasks for scientific  community. One of them is the utilization of higher operating frequencies in range of 140–150 GHz. This is an obvious way to obtain bigger channel capacity. However, for line-of-sight wireless channels, it may potentially lead to severe propagation losses, including absorption in water-containing atmospheric environments and scattering off static or dynamic objects. In this work, we report on the development of a technologically robust reflective surface that  can be used in the sixth-generation reflection-aided data links. The proposed reflective surface has 36×36 spiral metallic elements implemented on top of a thin back-metalized quartz plate. The fabricated prototype was designed for  50° deflections from specular propagation paths at angles of incidence within ±75° and successfully used for a non-distorting reflection of a 6º wide Gaussian beam at 145 GHz. It supports both linear and circular polarizations and exhibits cross-polarization level of approximately −25 dB.