A 1-bit Time-Modulated Reflectarray for Reconfigurable-Intelligent-Surface Applications
Xianbo Cao, Qiang Chen, Toru Tanaka, Masaki Kozai, Hiroya Minami
Abstract
The development of reconfigurable intelligent surfaces (RISs) is important to facilitate advances in beyond 5G and 6G technologies. However, the difficulty of controlling the reflected amplitude of the widely studied 1-bit reflectarray (RA) makes it difficult to meet the requirements of RIS for multiple application scenarios, and the change of the operating frequency in emerging time modulation (TM) technology-based RAs makes them unsuited to existing systems. Considering the observed the intrinsic similarities between the reflection states of 1-bit RA and logic states of 1-bit time function, a 1-bit time-modulated RA (1-bit TMRA) was designed based on a conventional 1-bit RA and TM technology in this study, and then was verified experimentally. The 1-bit RA characteristic was verified by realizing beam scanning, and the TM characteristic was verified by a shaping scattering pattern with ultralow sidelobe levels (SLLs). The results show that the proposed 1-bit TMRA is capable of realizing an extra TM characteristic without significantly increasing the system complexity of the 1-bit RA. Unlike most time-modulated arrays, the proposed 1-bit TMRA operates at the center frequency, making it suitable for direct application in existing wireless communication systems. These advantages highlight the potential of the proposed 1-bit TMRA for practical applications in RISs.