Microwave applications of single negative materials

Metamaterials are reviewed first according to two different standpoints. One is rather old way of classification, which pays attention to the tensor property of the material index and magnetoelectric interaction. The other one has an eye to the sign of the material index, shifting its viewpoint rather to application. Double negative materials that have both negative permittivity and permeability have attracted microwave engineers' interest because of its novel characteristics. Though the present article mentions its application a little, the emphasis is on the behavior of the surface wave along the periphery of a single negative material. Potential application to a directional coupler and a resonator will be discussed in some detail.