Design, Manufacturing, and Testing of a 20/30-GHz Dual-Band Circularly Polarized Reflectarray Antenna

This letter documents the design, manufacturing, and testing of a single-layer dual-band circularly polarized reflectarray antenna for 19.7–20.2 and 29.5–30.0 GHz. The reflectarray is designed using the concentric dual split-loop element and the variable rotation technique that enables full 360$^{\circ}$ phase adjustment simultaneously in two separate frequency bands. The elements have been optimized to suppress cross-polar reflection. Thereafter, the element data is included in a design tool that computes the reflectarray layout and the associated radiation patterns. The reflectarray is composed of 80$\,\times\,$80 elements printed on a $40\times 40{\hbox{-cm}}^{2}$ Rogers 5880 substrate. The antenna has been manufactured and measured at the DTU-ESA Spherical Near-Field Antenna Test Facility. The peak gain is 35.8 and 40.0 dBi at 20.0 and 29.8 GHz, respectively, and the aperture illumination efficiency is in the range of 53%–63% over the two frequency bands.