High-Gain Lens Antenna Using Transmissive Phase Gradient Metasurface

The Phase Gradient Metasurface (PGMS) is widely used in the flexible control of electromagnetic wave and the improvement of antenna gain. In this paper, a novel type of small-sized metasurface unit cell is designed, and the unit element adopts tri-layer metal and two-layer intermediate medium. Each layer of metal consists of a hexagonal outer ring and a regular hexagonal patch. By changing the metal patch side length, 360° transmissive phase shift is achieved in X-band. Then, according to the plane lens phase distribution principle, the PGMS with a focal length of 30 mm is formed by the above unit. Finally, the microstrip antenna is placed at the focus of the PGMS, and the PGMS converts the quasi-spherical wave radiated by the microstrip antenna into plane wave, thereby increasing the purpose of the antenna gain. The simulations show that the maximum gain of the antenna is increased by 12.3dB, and the E-plane half-power beamwidth is reduced by 74.3 degrees. Due to the hexagonal cell design, the number of PGMS unit cells can be effectively increased, and the antenna gain can be improved to the greatest extent.