350 GHz holographic surface for single- and multi-focusing

Reflectors are the preferred high-gain antenna for ground base stations and radar applications. However, they are bulky and heavy for airborne applications. Hence, planar arrays such as microstrip antenna arrays are favored in airborne use. Unfortunately, losses in the array feeding network are unacceptable at Terahertz (THz) frequencies due to the significant absorption of any material/substrate in this range (D. Grischkowsky et al., J. Opt. Soc. Am. B, 7, 2006, 1990). Therefore, high-gain reflectarrays are the preferred practical solution for high data rate THz airborne applications.