Scanning Characteristics of Metamirror Antennas With Subwavelength Focal Distance

We investigate beam scanning by lateral feed displacement in novel metasurface-based reflector antennas with extremely short focal distances. Electric field distributions of the waves reflected from the antenna are studied numerically and experimentally for defocusing angles up to 24°. The results show that despite their subwavelength focal distances, the scanning ability of the metamirrors is similar to that of short-focus reflectarrays (focal distance about several wavelengths). In addition to offering a possibility to realize extremely small focal distances, metamirror antennas are practically penetrable and invisible for any radiation outside of the operating frequency range.