Physically Consistent RIS: From Reradiation Mode Optimization to Practical Realization

TL;DR

This paper presents a practical framework for designing physically consistent reconfigurable intelligent surfaces (RIS) by optimizing reradiation modes, determining surface impedance, and validating through simulations and experiments.

Contribution

It introduces a comprehensive design process for RIS that ensures physical consistency, combining optimization, impedance design, and experimental validation.

Findings

Optimized RIS reradiation modes for coverage enhancement in Cape Town.

Designed RIS surface impedance and unitcells based on desired reradiation amplitudes.

Experimental measurements confirmed the theoretical and simulation predictions.

Abstract

We propose a practical framework for designing a physically consistent reconfigurable intelligent surface (RIS) to overcome the inefficiency of the conventional phase gradient approach. For a section of Cape Town and across three different coverage enhancement scenarios, we optimize the amplitude of the RIS reradiation modes using Sionna ray tracing and a gradient-based learning technique. We then determine the required RIS surface/sheet impedance given the desired amplitudes for the reradiation modes, design the corresponding unitcells, and validate the performance through full-wave numerical simulations using CST Microwave Studio. We further validate our approach by fabricating a RIS using the parallel plate waveguide technique and conducting experimental measurements that align with our theoretical predictions.