Indoor Channel Characterization using Transmitting and Reflecting RIS at mmWaves

In this paper, we present the results of a measurement campaign conducted in an indoor environment with multiple Reconfigurable Intelligent Surfaces (RISs), including a transmitting and a reflecting one in the Ka band. On the receiver side, a virtual array of monopole antennas is considered. The reconfiguration capabilities of both binary RISs are validated in various configurations, including different incidence/reflection angles and distances. A Multi Path Components (MPCs) extraction is performed in order to highlight the impact of RIS within a rich channel. Based on these results, we experimentally validated a general free-space multiple-input multiple-output (MIMO) channel transfer function with an arbitrary number of cascaded RISs, in either transmitting or reflecting modes, as well as a radar-range equation model.