A 2-D Beam-Scanning Circularly Polarized Folded Transmitarray Antenna With Linearly Polarized Feed for High Aperture Efficiency

Abstract

This letter presents a two-dimensional (2-D) beam-scanning circularly polarized (CP) folded transmitarray antenna (FTA) based on the Risley prism principle. By constructing transmitarray elements capable of linear-to-circular and circular-to-circular polarization conversion, and introducing a polarization-converting reflectarray surface, continuous 2-D beam scanning is achieved with a low-profile and high-aperture efficiency structure. A 2 × 2 linearly polarized patch array is adopted as the feed, which improves structural integration while ensuring gain performance. A prototype was fabricated to validate the design. The measured results demonstrate that at 10 GHz, continuous scanning from 0° to 49° in elevation and 0° to 360° in azimuth is achieved with a maximum gain loss of less than 3.5 dB and good circular polarization maintained during scanning. Furthermore, the antenna achieves a measured gain of 23.8 dBic and an aperture efficiency of 42.1% with an overall profile of only 1.84${{{\bm{\lambda }}}_0}$.