Some antenna applications of negative-refractive-index transmission-line (NRI-TL) metamaterials

Metamaterials are artificial structures engineered to exhibit unusual electromagnetic properties. Metamaterials (MTM) that exhibit a simultaneously negative electric permittivity /spl epsi/ and magnetic permeability /spl mu/, and thus a negative refractive index (NRI), have recently attracted considerable attention in the electromagnetic community. This has been motivated by the potential to create new microwave and antenna devices that exhibit superior characteristics compared to their conventional counterparts. A useful method for implementing planar metamaterials is based on reactively loaded transmission lines (TL). Such NRI-TE media consist of a network of printed transmission lines, periodically loaded with lumped-element series capacitors (C/sub o/) and shunt inductors (L/sub o/) in a dual-TL (high-pass) configuration. The planar nature of the TL-based metamaterial (MTM) structures renders them well suited for the realization of planar microwave antennas and circuits. This paper discusses some antenna applications of NRI-TL metamaterials.