Compensation for the influence of raindrops on the performance of a wireless system with a reconfigurable intelligent surface

Reconfigurable intelligent surfaces (RIS) is one of the promising technologies for increasing the throughput and expanding the coverage of existing and future wireless networks. It is expected that RIS will be actively used in outdoor scenarios, where it will be exposed to weather conditions such as rain. Rain, in turn, would affect the amplitude and phase frequency characteristics of the unit cells (UCs) that form the RIS, leading to a deterioration in the performance of the RIS wireless system in terms of the signal-to-noise ratio (SNR) at the receiver. This paper investigates the effect of rain of various intensity on the SNR at the receiver of a wireless system with RIS operating at a frequency of $4.8$ GHz. Also, a method is proposed to compensate for this effect by thickening the dielectric and subsequently adjusting the sizes of the UCs. It is demonstrated that the proposed compensation method reduces the SNR loss at the receiver to $0.9$ dB in rainy conditions.