Dynamic Modelling of Liquid Crystal-Based Metasurfaces and its Application to Reducing Reconfigurability Times

This paper describes and validates for the first time the dynamic modelling of Liquid Crystal (LC)-based planar multi-resonant cells, as well as its use as bias signals synthesis tool to improve their reconfigurability time. The dynamic LC director equation is solved in the longitudinal direction th...

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Bibliographic Details
Published in:arXiv.org 2022-09
Main Authors: Guirado, Robert, Perez-Palomino, Gerardo, Ferreras, Marta, Carrasco, Eduardo, Caño-García, Manuel
Format: Article
Language:English
Subjects:
Bias
Dynamic models
Finite element method
Inhomogeneity
Liquid crystals
Mathematical analysis
Metasurfaces
Modelling
Phase control
Strata
Tensors
Time dependence
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Summary:This paper describes and validates for the first time the dynamic modelling of Liquid Crystal (LC)-based planar multi-resonant cells, as well as its use as bias signals synthesis tool to improve their reconfigurability time. The dynamic LC director equation is solved in the longitudinal direction through the finite elements method, which provides the z- and time-dependent inhomogeneous permittivity tensor used in an electromagnetic simulator to evaluate the cells behaviour. The proposed model has been experimentally validated using reflective cells for phase control (reflectarray) and measuring the transient phase, both in excitation and relaxation regimes. It is shown how a very reduced number of stratified layers are needed to model the material inhomogeneity, and that even an homogeneous effective tensor can be used in most of the cases, which allows a model simplification suitable for design procedures without losing accuracy. Consequently, a novel bias signal design tool is proposed to significantly reduce the transition times of LC cells, and hence, of electrically large antennas composed of them. These tools, similar to those used in optical displays, are experimentally validated for the first time at mm- and sub-mm wave frequencies in this work, obtaining an improvement of orders of magnitude.
ISSN:2331-8422
DOI:10.48550/arxiv.2209.14597