Metamaterials - A Challenge for Contemporary Advanced Technology

The permittivity, permeability and conductivity of a material characterize its ability to interact with an electromagnetic field. In nature, the magnitudes of these three quantities are restricted mostly to positive values. In contrast, metamaterials are artificially produced composite media exhibiting electromagnetic responses that natural materials do not provide. They enable the three constitutive parameters to be cast down to negative values. Nowadays, electromagnetic metamaterials is a rapidly growing research domain involving electromagnetism, microwave and millimeter wave technology, optics, material technology and nanotechnology. There are prospects for many challenging practical applications. A historical survey of the evolution of metamaterials from the earliest assumptions until the current state of the art introduces discussion upon the metamaterials, description of their characteristics and behavior. Metamaterials are known in two forms. An inherent metamaterial is a real 3D solid volumetric medium. 1D or 2D planar circuits are the second version of metamaterials. The first form is characterized by field theory, while the second form utilizes transmission line theory. Manifold applications of guided waves, radiated waves, new microwave circuits, devices and structures will be discussed from the engineering point of view. There is a brief report on the authors' innovative findings. This involves both theoretical and experimental results that have been achieved in recent years. In particular, it concerns the utilization of split ring resonators in negative permeability metamaterials, the concept and the production of an isotropic negative permeability medium, an isotropic negative permittivity medium, CPW supporting propagation of a left-handed wave, and wire media exhibiting negative permittivity. Finally, prospects for further developments in this interesting field are presented.