Media, electromagnetic characteristics

Abstract

In macroscopic media, the electric displacement field and magnetic induction can be related to the electric intensity and magnetic intensity in ways quite different from that in vacuum. With increasing complexity, the medium can be characterized as isotropic, anisotropic, and bianisotropic. All media are dispersive in that the phase velocity of a wave depends on the frequency. The real and imaginary parts of the frequency-dependent complex permittivity are related by the Kramers-Kronig relations, which are very useful in all areas of physics. In characterizing the electromagnetic properties of an inhomogeneous medium, the effective-medium approximation is useful within its region of validity. Beyond that, the method base on the self-consistency condition can be employed. In terms of artificial materials, metamaterial is a new class of artificially constructed electromagnetic material that can exhibit electromagnetic properties difficult or impossible to find in conventional materials, which leads to totally new electromagnetic phenomena.