Applications of negative-refractive-index transmission-line (NRI-TL) metamaterials in planar antennas and their feed networks

Negative-refractive-index transmission-line (NRI-TL) metamaterials are introduced and their fundamental properties are described. Following this, various applications using NRI-TLs are shown and their salient characteristics described. First, a broadband microstrip balun is shown, then a broadband 1:4 power divider, followed by a series-fed linear dipole array that exhibits reduced beam squinting, then a leaky-wave antenna with reduced beam squinting is presented and finally an electrically small ring antenna is shown that exhibits vertical linear polarization.