A Prototype of Reconfigurable Intelligent Surface with Continuous Control of the Reflection Phase

Abstract

With the development of the next generation of mobile networks, new research challenges have emerged, and new technologies have been proposed to face them. On one hand, the reconfigurable intelligent surface (RIS) technology is being investigated for partially controlling the wireless channels. RIS is a promising technology for improving the signal quality by controlling the propagation of the electromagnetic waves in a nearly passive manner. On the other hand, ambient backscatter communications (AmBC) is another promising technology that is tailored to address the energy efficiency requirements of the Internet of Things. AmBC enables low-power communications by backscattering the ambient signals and thus reusing existing electromagnetic waves for communications. RIS can be utilized in the context of AmBC for improving system performance. In this article, we report a prototype of an RIS that offers the capability of controlling the phase shifts applied to the incident waves in a continuous manner, and we characterize its properties with the aid of full-wave simulations and through experimental measurements. Specifically, we introduce a phase shift model for predicting the signal reflected by the designed RIS prototype. We apply the proposed model for optimizing an RIS-assisted AmBC system, and we demonstrate that the use of an RIS can significantly improve system performance.