70‐3: Tunability of Reconfigurable Intelligent Surface (RIS) using Liquid Crystal (LC) according to Various Bias Voltage Levels

Abstract

This paper introduces a proof‐of‐concept of RIS consisting of Merck GT7‐29001 Liquid Crystal (LC) and Corning glass with metallic circle patterns for controlling redirection at Ka‐band. Since this structure and fabrication process is compatible with conventional LCD manufacturing technology, significant cost reduction and large size capability can be expected compared to incumbent diode & PCB substrate fabrication process. The prototype of RIS had LC layer of a 200um thickness and its frequency tunability was over 14% when inducing bias voltages up to 25V at metal patterns. Simulation results using dielectric properties of GT7‐29001 show a good agreement with the frequency tunability at measurements. Also, 23° beam steering was realized by separately inducing 0V or 10V at each metal pattern on glass.

18‐2: A Novel Design for Reconfigurable Intelligent Surfaces (RIS) with Thin Liquid Crystal Layer for Wireless Communications

“…To alleviate the shortcomings of conventional RIS using semiconductor-based devices, researchers [6][7][8][9] have proposed reconfigurable mmWave devices based on liquid crystal (LC). These referenced papers are studies where researchers controlled the reflection angle by changing the reflection phase of the unitcells.…”

Rapid Prototyping of Anomalous Reflective Metasurfaces Using Spray-Coated Liquid Metal

“…Reconfigurable intelligent surfaces (RISs) promise to improve coverage for signals negatively impacted by obstructions present in the line-of-sight (LOS) path, making them an attractive technology for 5G and beyond mobile communications [1]. A typical RIS combines passive reflective elements with active devices such as varactors [2][3][4][5] or PIN diodes [6][7][8][9], while others use phase-tunable materials such as liquid crystals [10][11][12], 2D materials [13][14][15][16][17], or phase-change materials [18,19]. Creating a tunable reflection phase gradient across a surface enables the RIS to dynamically redirect an incoming signal to an anomalous direction not predicted by Snell's Law.…”