Glossary
Antennas and metamaterials

Metamaterial

An artificial material with physical properties that exceed those of natural materials.

Left-handed material

A material in which the phase velocity of an electromagnetic wave is negative. The refractive index of this material is real but negative.

Metasurface

A two-dimensional structure typically consisting of metallic patterns on a dielectric substrate. Metasurfaces are the successors to both frequency-selective surfaces and metamaterials. They are used in both optics and microwave applications for their filtering, phase-shifting, reflection, transmission, and absorption properties.

Group velocity

The propagation speed of a wave packet. This speed remains positive in a left-handed material. In some cases, this speed may also exceed the speed of light in a vacuum.

Phase velocity

The rate at which the phase of a wave changes....