Active transmitarray antenna based on near-zero-index metalens

By combining a transmitarray-based controllable phase-delay surface with a near-zero-index collimating metalens, a compact, high-gain, upper-hemisphere scanning antenna can be constructed. The ability of the ZIM lens to produce a nearly uniform field amplitude and phase across its surface provides an efficient input for the transmitarray phase-control surface, which can then simply be controlled by addressing the appropriate rows and columns.