Single-Layer Ultrathin Reflectarray Antenna With Independently Controllable Dual Beams

This paper proposes an X-band single-layer ultrathin low cross-polarization level reflectarray antenna with independently controllable dual beams. The unit cell of the reflectarray consists of a phase control layer, a dielectric plate and a metal plane. The phase control layer is composed of a cross patch and a metal grid. Four slots are etched on the cross patch, and independent beam control of dual-linear polarization electromagnetic (EM) waves can be achieved by adjusting the length of the cross patch. The metal grid reduces the coupling between adjacent unit cells to ensure stable phase compensation. The reflection elevation angles for the two polarization beams are ±15°. The measured results show that the 2 dB gain bandwidth of x- and y-polarizations are 18.2% and 18%, and the 3 dB gains of x- and y-polarizations are 21% and 21.3%, respectively. The reflectarray's bandwidth can be further improved with an increase of the reflectarray's thickness. The cross-polarization levels were all below –37.5 dB. The proposed reflectarray antenna can realize the independent control of broadband dual-polarized beams in an ultra-low profile (0.069λ), which is a very competitive solution for the satellite applications and scenarios requiring lightweight.