Scanning properties of novel metasurface-based reflector antennas

Abstract

We investigate beam scanning by lateral feed displacement in novel metasurface-based reflector antennas (metamirrors) with extremely short focal distances which emulate a cylindrical PEC reflector. Two reciprocal cases of illumination are explored: illumination by a plane wave (focusing to a line) and illumination by a source of cylindrical waves from the focal line (plane wave in reflection). For the former case, the power density distribution of the reflected waves from the metamirror are studied numerically for scanned beam angles up to 10° from the normal for two ratios of the focal distance and the diameter. For the latter, electric field distributions of waves reflected from the antenna are explored numerically and experimentally for defocusing angles up to 16°. The results show that despite extremely small focal distances, the scanning ability of metamirrors is similar to that of comparable reflectarrays. In addition to offering a possibility to realize extremely small focal distances, metamirror antennas are practically invisible for any radiation beyond the operating frequency range.