Wideband Bifocal Dielectric Transmitarray

In this paper, some numerical results on the scanning capabilities of a bifocal dielectric transmitarray (TA) are presented. The TA surface has been discretized with three-layer unit cells: the central one presents a varying size square hole, used to control the phase of the transmission coefficient, while the two identical, external layers are characterized by a truncated pyramid hole and they act as matching elements. The computed antenna radiation patterns stay quite stable of an angular range of ±40°, keeping in each of the considered direction of maximum radiation a 1-dB gain bandwidth larger than 23%.