Ku-Band Phase-Gradient Metasurface for Broadband High-Gain Circularly Polarized Lens Antenna.

In this paper, a novel broadband high-gain, circularly polarized planar lens antenna is presented. We used the rotation elements to design a transmission-type polarization conversion planar phase-gradient metasurface (PPGM). By adjusting the rotational angles of the metal patch on the element, we obtained the desired transmission phase shift for PPGM. We used a patch antenna as a feed source, which formed a lens antenna system integrated with the PPGM. The simulation results showed that the PPGM can achieve a high-efficiency, cross-polarization conversion for vertical incidence of a right-handed circularly polarized plane wave. Our numerical and experimental results agreed well with each other, indicating that the antenna system had a peak gain of 18.8 dB, a good axial ratio better than 2 dB at 13 GHz, with an aperture efficiency of 50.56% and a focal length/diameter (F/D) ratio of 0.307. In addition, its -10 dB impedance and 3dB axial ratio bandwidth reached up to 940 MHz. The lens antenna performed well and can be applied in many communication systems. [ABSTRACT FROM AUTHOR]