Enhancement of inductance along metallic mesh wires in three-dimensional quasi-isotropic metamaterials using high-ε dielectric particles for impedance-matching with free space

Takuya Yamaguchi,Tetsuya Ueda,Takumi Ishiyama,Tatsuo Itoh

doi:10.1051/epjam/2019019

Abstract

In this paper, we consider cube-shaped unit cells including high-ε dielectric cubes under magnetic dipole-like resonance placed at the center and metallic mesh wires for negative permittivity to construct three-dimensional quasi-isotropic metamaterials in the microwave region. Basically, such structures suffer from their low wave impedance due to inclusion of high-ε materials. To reduce effective permittivity of the composite structures, we propose to insert additional inductance into the metallic mesh. For the insertion of lumped inductors along the wires, dispersion diagram and the Bloch-impedance are numerically estimated, and converted to effective permittivity and permeability. The numerical simulation results clearly show almost 3-D isotropic propagation characteristics in a specific frequency region and enhancement of the Bloch-impedance close to free space in the left-handed region. The lumped inductors are replaced by meander-line strip patterns for practical configurations. The metallic patterned structures also achieve the enhanced Bloch impedance that is well-matched to free space.

Highlights

Negative-refractive-index (NRI) or left-handed (LH) metamaterials can be realized by making the effective permeability and permittivity negative simultaneously [1], and have been investigated for applications to super lenses, cloaking techniques, antennas, and so forth [2,3,4,5]
Most of bulky LH metamaterials were made of metallic patterns, such as a combination of split-ring resonators (SRRs) and thin metallic wires [6], lumped capacitors inserted in the metallic mesh wires [7], transmission line networks [8,9,10], and so forth
The lumped inductors are replaced by meander-line strip patterns for practical configurations to achieve the 3-D quasi-isotropic metamaterials impedance-matched to free space

Summary

Introduction

Negative-refractive-index (NRI) or left-handed (LH) metamaterials can be realized by making the effective permeability and permittivity negative simultaneously [1], and have been investigated for applications to super lenses, cloaking techniques, antennas, and so forth [2,3,4,5]. We proposed dielectric-based 3-D left-handed metamaterials impedance-matched to free space and confirmed that backward wave propagation characteristics were observed without serious reflections and scatterings in the measurement [30]. It was focused mainly on the experimental demonstration and the detail design procedures for the metamaterials were not discussed there. We consider cube-shaped unit cells including a high-e dielectric cube under the magnetic dipole resonance placed at the center and metallic mesh wires wrapping the dielectric cubes for negative permittivity in order to construct 3-D quasi-isotropic left-handed metamaterials impedance-matched to free space. The lumped inductors are replaced by meander-line strip patterns for practical configurations to achieve the 3-D quasi-isotropic metamaterials impedance-matched to free space

Composite structures loaded with lumped inductors

Composite structure loaded with printed meander-line patterns

Findings

Conclusion