Artificial gradient-index lens based on single unit cell layer fishnet metamaterial for phase correction of a horn antenna

An artificial gradient-index lens for phase correction of a horn antenna in the Ka-band is presented. By introducing a gradient of the geometric features in the single layer fishnet unit cell, a phase variation between −180 and +180 degress can be obtained. The relation between the geometric dimensions, phase- and amplitude distribution is presented. Furthermore, phase-correction and resulting improved radiation pattern is demonstrated at 27.5 GHz and evaluated by nearfield measurements making the presented single layer fishnet a good candidate for artificial lenses with low weight and low fabrication costs.