Dispersion Analysis of Periodic Structures in Anisotropic Media: Application to Liquid Crystals

TL;DR

This paper introduces a versatile method for computing dispersion diagrams in anisotropic media, enabling analysis of complex structures like liquid crystal-based microwave devices using commercial simulators.

Contribution

The method extends commercial eigenmode solvers to handle non-diagonal anisotropic tensors, lossy materials, and unbounded structures, specifically applied to liquid crystal configurations.

Findings

Validated with CST and HFSS software.

Analyzed dispersion in various liquid crystal structures.

Enabled study of leaky-wave antennas with anisotropic media.

Abstract

This paper presents an efficient method to compute the dispersion diagram of periodic and uniform structures with generic anisotropic media. The method takes advantage of the ability of full-wave commercial simulators to deal with finite structures having anisotropic media. In particular, the proposed method extends the possibilities of commercial eigenmode solvers in the following ways: (i) anisotropic materials with non-diagonal permittivity and permeability tensors can be analyzed; (ii) the attenuation constant can easily be computed in both propagating and stopband regions and lossy materials can be included in the simulation; and (iii) unbounded and radiating structures such as leaky-wave antennas can be treated. The latter feature may be considered the most remarkable, since the structures must be forcefully bounded with electric/magnetic walls in the eigensolvers of most commercial simulators. In this work, the proposed method is particularized for the study of liquid crystals (LCs) in microwave and antenna devices. Thus, the dispersion properties of a great variety of LC-based configurations are analyzed, from canonical structures, such as waveguide and microstrip, to complex reconfigurable phase shifters in ridge gap-waveguide technology and leaky-wave antennas. Our results have been validated with previously reported works in the literature and with commercial software CST and HFSS.