Bifocal Design and Aperture Phase Optimizations of Reflectarray Antennas for Wide-Angle Beam Scanning Performance

A new design methodology is proposed for high-gain beam-scanning reflectarray antennas. Various approaches for designing beam-scanning reflectarray antennas are first reviewed and it is shown that for limited scan coverage, utilizing the feed displacement technique is a convenient design approach. To improve the scan coverage, a single-reflector bifocal aperture phase distribution is proposed for the reflectarray antenna, and is further optimized to improve the beam-scanning performance. Four reflectarray prototypes, each corresponding to a specific aperture phase distribution, have been fabricated and tested. A Ka-band reflectarray antenna with 60 degrees scan coverage achieving 30-dB gain and side-lobe level below 15 dB is demonstrated.