Study On Planar Array Antenna Based On Phase Gradient Metasurface

Low-profile high-gain antenna has always been one of the research topic in the field of antenna application.Especially in recent years,because of its planar structure,the research of phase gradient metasurface as a low profile antenna has attracted the attention of many scholars.At present,almost all the research focuses on exploring the feeding technology to realize its radiation.Based on this,the suspended microstrip feeding technology and lowprofile discontinuous transmission line feeding technology are proposed in this paper,which are used to realize high-gain and extremely low-profile phase gradient metasurface antennas respectively.The main contents are as follows:1)Research on high-gain phase gradient metasurface antenna with suspended microstrip-like feed.A suspended microstrip feeding technology is proposed and its feasibility to realize high-gain phase gradient metasurface antenna is studied.The feeding technology requires that the feeding structure consists of rectangular waveguide and suspended microstrip structure,the rectangular waveguide is mainly used for feeding and matching,and the suspended microstrip runs through the whole phase gradient super surface.It is found that the radiation efficiency of the antenna can be improved by symmetrically placing the phase gradient metasurface resonant units on both sides of the suspended microstrip,and adjusting the arrangement of the resonant units according to the field distribution,thus increasing the gain of the antenna.In order to verify the feasibility of this feeding technology,we designed a phase gradient metasurface antenna with this technology.The impedance bandwidth of the phase gradient metasurface antenna is 9.06-12.30 GHz,the relative bandwidth is 30.3%,and the maximum practical gain is 22.30 dBi;Compared with similar phase gradient metasurface antennas in the same frequency band,the bandwidth is expanded by 7.3%,and the realized gain is increased by 6.06 dB.2)Study on phase gradient metasurface antenna with coplanar discontinuous transmission line feeding technology.A coplanar discontinuous transmission line feeding technology is proposed,and the feasibility of using this technology to realize a very low profile phase gradient metasurface antenna is studied.The feeding technology requires that the feeding structure consists of 12 uniform and discontinuous rectangular rings.It is found that by placing the coplanar discontinuous transmission line feeding technology and the phase gradient metasurface in the same plane,and symmetrically placing the phase gradient metasurface resonant units on both sides of the feeding structure,the profile height of the antenna can be reduced and the antenna can radiate efficiently.In order to verify the feasibility of this feeding technology,a very low profile phase gradient metasurface antenna is designed,and the antenna is processed and tested.It’s impedance bandwidth is 700MHz(10.48-11.18GHz).Within the impedance bandwidth,the realized gain is all above 12dBi,and the maximum realized gain is 14.19 dBi.This antenna can be used in situations where the requirement of gain is not high but the requirement of low profile is very high.