Error Analysis of Programmable Metasurfaces for Beam Steering

Hamidreza Taghvaee,Julius Georgiou,Albert Cabellos-Aparicio,Sergi Abadal

doi:10.1109/jetcas.2020.2970077

Abstract

Recent years have seen the emergence of programmable metasurfaces, where the user can modify the EM response of the device via software. Adding reconfigurability to the already powerful EM capabilities of metasurfaces opens the door to novel cyber-physical systems with exciting applications in domains such as holography, cloaking, or wireless communications. This paradigm shift, however, comes with a non-trivial increase of the complexity of the metasurfaces that will pose new reliability challenges stemming from the need to integrate tuning, control, and communication resources to implement the programmability. While metasurfaces will become prone to failures, little is known about their tolerance to errors. To bridge this gap, this paper examines the reliability problem in programmable metamaterials by proposing an error model and a general methodology for error analysis. To derive the error model, the causes and potential impact of faults are identified and discussed qualitatively. The methodology is presented and exemplified for beam steering, which constitutes a relevant case for programmable metasurfaces. Results show that performance degradation depends on the type of error and its spatial distribution and that, in beam steering, error rates over 20% can still be considered acceptable.

Highlights

Metamaterials have garnered significant attention in the last decade as they enable unprecedented levels of electromagnetic (EM) control [1] and have opened the door to disruptive advances across domains such as imaging, integrated optics, or wireless communications [2]–[5]
Since random coding [51] leads to random scattering, we argue that uncorrelated random errors generate scattering that does not accumulate as a large secondary lobe
This paper has proposed a general methodology for the error analysis of programmable metasurfaces, where faults are distinguished by their impact on individual unit cells and their spatial distribution across the metasurface

Summary

Introduction

Metamaterials have garnered significant attention in the last decade as they enable unprecedented levels of electromagnetic (EM) control [1] and have opened the door to disruptive advances across domains such as imaging, integrated optics, or wireless communications [2]–[5]. Metasurfaces, the thin-film analog of metamaterials, are generally comprised of a planar array of subwavelength elements over a substrate, i.e. the unit cells, and inherit the unique properties of their 3D counterparts while minimizing bulkiness, losses, and cost Functionalities such as beam steering, focusing, vorticity control, or RCS reduction have been demonstrated across the spectrum, from microwaves [6]–[8] to terahertz [9]–[13], or optical frequencies [14], [15]. Works in the field of metamaterials had two main drawbacks, namely, non-adaptivity and non-reconfigurability This is because, due to their highly resonant nature, unit cells are generally designed for a particular EM function and scope.

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