All-dielectric steerable leaky-wave THz antenna

Epsilon Near Zero (ENZ) and Zero Index Metamaterials (ZIM) offer remarkable behaviors such as tailoring the radiation phase pattern, tunneling of waves through channels and bends, and directive emission of sources (Enoch et al., Phys. Rev. Lett., 2002), demonstrated both in theory and experiments. The directive emission effect is due to a unique and simple refracting feature that ZIMs offer. An oblique incident wave going from the ZIM to air refracts with a smaller angle to the normal at the interface. This is due to the transverse wave-number matching and Snell´s law. With air having the higher refractive index than the ZIM, the angle of refraction in air is smaller than in the ZIM. If a radiator is embedded inside the ZIM, the waves exiting the ZIM are collimated, causing a highly directive beam.