Miniaturized-Element Offset-Feed Planar Reflector Antennas Based on Metasurfaces

In this letter, we propose a low-profile planar reflector antenna based on metasurfaces. Metasurfaces are planar version of metamaterials, which are composed of 2-D arrays of subwavelength elements. Due to the subwavelength nature, metasurface-based reflector antenna can be made much thinner and grating lobes can be further suppressed. As an example, a 400 × 400-mm ² offset-fed planar reflector with a focal length F = 300 mm is designed to mould spherical wavefronts into planar ones at 10.0 GHz. The thickness and element spacing is less than λ ₀ /15 and λ ₀ /6, respectively. Moreover, due to symmetry of the element, the planar reflector is polarization-independent. A prototype was fabricated and measured. Both the simulated and measured results show that the planar reflector antenna can achieve a narrow main lobe and operate over 9.5-10.5 GHz with gain larger than 23 dB.