METAMATERIALS

MARÍA FERNÁNDEZ FERNÁNDEZ AND ANA ARNAIZ 4ºC

INTRODUCTION

• Metamaterials are artificial materials engineered to have properties that have not yet been found in nature. They are assemblies of multiple individual elements fashioned from conventional materials such as metals or plastics, but the materials are usually constructed into repeating patterns, often with microscopic structures. Metamaterials derive their properties not from the compositional properties of the base materials, but from their exactingly-designed structures. Their precise shape, geometry, size, orientation and arrangement can affect waves of light (electromagnetic radiation) or sound in a manner not observed in natural materials.

ELECTROMAGNETIC METAMATERIALS

• An electromagnetic metamaterial affects electromagnetic waves incident on it via structural features that are smaller than the wavelength of the respective electromagnetic wave. To behave as a homogeneous material accurately described by an effective refractive index, its features must be much smaller than the wavelength.

CLASSIFICATION

• Electromagnetic metamaterials divide into different classes, as follows:

-Negative index

-Single negative

-Electromagnetic bandgap

-Double positive medium

-Bi-isotropic and bianisotropic

-Chiral

-FSS based

OTHER TYPES OF METAMATERIALS

• Elastic: these are a type of metamaterial that uses different parameters to achieve a negative index of refraction in materials that are not electromagnetic.

• Acoustic: acoustic metamaterials control, direct and manipulate sound in the form of sonic, infrasonic, or ultrasonic waves in gases, liquids and solids. As with electromagnetic waves, sonic waves can exhibit negative refraction.

Hybrid elastic metamaterials Acoustic metamaterials

APPLICATIONS

-Antennas: are a class of antennas that use metamaterials to improve performance.

-Absorber: a metamaterial absorber manipulates the loss components of metamaterialspermittivity and magnetic permeability, to absorb large amounts of electromagnetic

radiation.-Superlens: uses metamaterials to achieve resolution beyond the diffraction limit.-Cloaking devices: metamaterials are a potential basis for a practical cloaking device.-Seismic protection: seismic metamaterials counteract the adverse effects ofseismic waves on man-made structures.-Light and sound filtering: metamaterials textured with nanoscale wrinkles couldcontrol sound or light signals, such as changing a material's color or for improvingultrasound resolution.

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