A 2-D Beam-Scanning Circularly Polarized Folded Reflectarray Antenna Based on Risley Prism at X-Band

In this communication, we present a new design for a folded reflectarray antenna (FRA) inspired by the Risley prism antenna. This innovative FRA enables circularly polarized (CP) beam scanning in both azimuth and elevation planes with low losses. The proposed CPFRA comprises of a top layer with a circularly polarized selective surface (CPSS), a bottom layer with an RA, and a planar CP antenna serving as the feed antenna. The CPSS has the capability to fully reflect the incident waves of right-hand circular polarization (RHCP) while transmitting those of left-hand circular polarization (LHCP). By mechanically rotating both the CPSS and RA, this antenna enables beam scanning in the elevation plane from 0° to 45°, as well as in the azimuth plane from 0° to 360°. At a frequency of 10 GHz, measurements show that this antenna achieves an impressive maximum gain of 21.5 dBic, corresponding to an aperture efficiency (AE) of 31.2%. This antenna offers several advantages, including its compact structure, low profile, low cost, and high gain performance. As such, it proves suitable for applications where space is limited, such as satellite communication and vehicle communication.