Fresnel Lens Antennas with smooth phase compensation and manufactured with a very low cost technological process in the 220 - 330 GHz band

In this paper, the performance of Fresnel Lens Antennas (FLAs) is investigated in the 220–330 GHz band for future high-data-rate wireless communication systems. The lenses are fabricated through an innovative and highly cost-effective method based on thermally pressed foam material. This technique enables the realization of fully dielectric, inhomogeneous lenses from a single material, allowing smooth phase compensation for the wavefront distortion introduced by a primary feed, in this case a standard horn antenna. After detailing the technological process, the horn antenna is designed and experimentally validated, demonstrating excellent agreement between simulated and measured results in terms of radiation patterns and gain. Several FLAs are then fabricated, confirming the effectiveness of the pressed foam approach over the entire operating band. One of the prototypes, featuring a 30 mm diameter, achieves a narrow half-power beamwidth of 2° and a peak gain of 32 dBi when implemented using three stacked sub-lenses.