Ultrathin broadband focusing metasurface for high-gain antenna application with high efficiency

We propose a new ultrathin broadband metasurface to manipulate electromagnetic wavefront and take it into application for high-gain antenna. The symmetrical element is composed of orthogonally I-shaped structures and a meta-grounded plane spaced by a dielectric isolator, with the thickness of about 1/10 wavelength. The proposed metasurface transforms the quasi-spherical wave emitted by the Vivaldi antenna pointed at focal point to plane wave successfully. Both simulation and test results show that peak gain of planar antenna has been averagely enhanced by 16dB during the -1dB gain bandwidth of 15-22GHz, resulting in a 45% aperture efficiency at 18GHz.