An FSS-Backed 20/30 GHz Circularly Polarized Reflectarray for a Shared Aperture L- and Ka-Band Satellite Communication Antenna

A shared aperture antenna for simultaneous operation at L- (1525 to 1661 MHz) and Ka-band (19.7 to 20.2 GHz and 29.5 to 30.0 GHz) is demonstrated. This stacked antenna consists of a Ka-band reflectarray antenna with a frequency selective surface (FSS) ground-plane above an L-band patch array antenna. The reflectarray is based on the concentric dual split-loop element backed by a concentric dual-loop FSS element. The reflectarray comprises 80 × 80 elements and it is printed on a 40 ×40 cm² Rogers 5880 substrate, while the L-band antenna is a 2 × 2 patch array. The reflectarray antenna has been manufactured at the Technical University of Denmark (DTU) and measured at the DTU-ESA Spherical Near-Field Antenna Test Facility. The reflectarray provides a maximum directivity of 36.4 and 38.5 dBi at 20.0 and 29.8 GHz, respectively, and an aperture illumination efficiency in the two frequency bands up to 57% and 48%, respectively. There is very little degradation in the L-band patch array performance due to the reflectarray, and it provides a minimum directivity of 11.8 dBi over the L-band.