Bifocal Design Procedure for Dual-Reflectarray Antennas in Offset Configurations

This letter presents a new bifocal design procedure for dual-reflectarray antennas (DRAAs) in offset configurations. The technique starts by considering an axially symmetric geometry with the reflectarrays placed in parallel planes, which allows the rotation of a two-dimensional bifocal design around the symmetry axis. To reach a more compact configuration and to obtain smoother phase distributions, the reflectarrays are tilted and their phases are adjusted by means of a ray-tracing routine. The technique has been validated by numerical simulations through the comparison with a previous center-fed dual-reflectarray prototype. Finally, the simulations of an offset DRAA with tilted reflectarrays are presented, providing 0.56° beam spacing at 20 GHz for multispot satellite applications in Ka-band.