Beam-scanning improvement of reflectarrays using single-layered sub-wavelength elements

This paper studies the use of double concentric circular ring elements arranged in a sub-wavelength grid on a single layer of substrate, in an effort to enhance the beamscanning capability of reflectarrays. The work is carried out at 10 GHz on a 405mm×405mm aperture. In addition to a broad gain bandwidth, the reflectarray with a sub-wavelength grid demonstrates a superior beam-scanning performance compared to the one with λ/2 grid. The measured results show that the reflectarray with 0.3λ grid spacing realizes a 1-dB gain bandwidth of 22% with an aperture efficiency of 56.6%. With the reflectarray fixed, this paper investigates the possibility of beam scanning by displacing the feed horn laterally. The results show that beam scanning of ±15o is possible while retaining the broadband characteristics.