The utility of negative refractive index metamaterials as passive UHF RFID tag inlays

Recently, there has been much work in exploring the physics of negative refractive index (NRI) metamaterials [1, 2] as applicable experimentally. NRI metamaterials are fabricated materials that have negative permittivity (εr) and permeability (μr) values. These materials were first suggested in 1967 by Vaselago [3], where they were theoretically studied to reach the proposed conclusion that such mediums should be deemed as possessing negative refractive indexes since (n = −√Εμ). This proposal endured many criticisms, due to the unconventional utilization of physical concepts and non-existence of materials possessing these behaviors at that time. In the last decade, the study of NRI metamaterials (NRM) has experienced huge interests spanning both theoretical and experimental physicist. This recent excitement is due to the fact that NRM's have now been discovered experimentally through fabrication techniques utilizing the combination of a −μr and a −εr material(s) [1]. Furthermore, the prediction and verification by Pendry [4] that NRM's could be utilized as perfect lenses with higher resolutions than conventional lenses provided the required breakthrough.