Recent developments in exotic materials: negative permittivity and permeability, nonreciprocal composites

In this review paper we discuss some new and exotic composite materials for the use at microwave frequencies. Recently, electromagnetic materials with negative permittivity and permeability values (sometimes called also "media with negative refraction index") have been given much attention in the literature. Here we show that using small dipole and loop antennas loaded by certain simple electronic circuits as composite inclusions, the material behaves as an effective medium with real negative parameters in wide frequency bands. Similarly, thin sheets of negative materials can be simulated by strip or patch arrays loaded by active circuits. Some properties of electromagnetic waves in structures containing layers of media with negative parameters are outlined. In particular, plane waveguides and one-dimensional electromagnetic band gap structure containing these new materials are considered. In the last part of the paper we describe new nonreciprocal electromagnetic stop band structures.