Electromagnetic Wave Propagation in Media with Indefinite Permittivity   and Permeability Tensors
  We study the behavior of wave propagation in materials for which not all of the principle elements of the permeability and permittivity tensors have the same sign. We find that a wide variety of effects can be realized in such media, including negative refraction, near-field focusing and high impedance surface reflection. In particular a bi-layer of these materials can transfer a field distribution from one side to the other, including near-fields, without requiring internal exponentially growing waves. 
D. R. Smith and D. Schurig