Stacked cut-off hole arrays for lens antennas at subterahertz frequencies

further development of metallic lenses may benefit from extraordinary transmission metamaterials which are susceptible of being free-space matched, in contrast to classical metallic lenses based on apertures above cut-off, and require thinner profiles, reducing volume and weight. Experimental demonstration of enhancing directivity capabilities at millimetre-waves is reported for both n = 1 and n 0 regimes, whereas they can be also foreseen at higher frequencies because of the scalability of this approach.