Wideband Wide-Angle Scanning Metasurface Antenna

In recent years,with the rapid development of electronic communication technology,the requirements for antenna performance have become increasingly higher.The discovery of metamaterials and metasurfaces has provided solutions to the challenges encountered in antenna design.Metasurface is a two-dimensional planar structure of metamaterials,which also has special electromagnetic characteristics of metamaterials,reducing space occupation and facilitating conformity.Metasurface antenna arrays often use free-space feeding,which causes different spatial phase delays of the antenna at different frequencies,and the bandwidth of the metasurface unit is usually narrow,so its operating frequency band is generally narrow.At the same time,the method for implementing beam scanning of metasurface antennas mostly uses mechanical rotation,and the phase distribution of the array is fixed,so the gain will decrease significantly during large-angle beam scanning.In practical antenna applications,wideband and wide-angle beam scanning performance is usually required.Therefore,it is of research significance to design a wideband and wide-angle beam scanning metasurface antenna to solve the above problems.The main research content of this article is as follows:1、In order to solve the problem of narrow phase coverage of wideband transmission array antenna units consisting of only two layers of metal printed on a single layer of dielectric,a method of adding metal cylinders to the unit is adopted to broaden the phase coverage range of the superstrate transmission array unit in the operating frequency band.The phase distribution at different frequencies is optimized to reduce the phase error within the operating frequency band,thus achieving a 1 d B gain bandwidth of 22.2%,with a unit profile height of only 0.13λ₀.2、In order to address the narrow bandwidth of active superstrate reflection array antenna units,a dual-layer microstrip metal patch structure is designed to broaden the operating bandwidth of the active superstrate reflection array antenna unit.The active structure of the unit is a PIN diode,which has only two working states:ON and OFF.Therefore,the compensation phase needs to be divided into two states,which is 1-bit phase compensation.The unit can achieve 180°±20°phase control in the frequency band of 11.5 GHz～15.4 GHz,with a relative bandwidth of about 28.9%.The active metasurface reflectometer array antenna is fabricated and tested.The 3 d B gain bandwidth is about 39.5%,and the gain drop of two-dimensional beam scanning to 60 degrees is about 2.8 d B,which has wide gain bandwidth and large beam scanning Angle.3、Compared with linearly polarized antennas,circular-polarized antennas have stronger anti-interference performance and wider application scenarios,so a circular-polarized active metasurface reflection array antenna is designed.The active structure of the circular-polarized metasurface reflector array element is that two PIN diodes are placed at the bottom of the metasurface antenna element.The working state of the two diodes on the element is controlled by controlling the DC voltage,and the principle of controlling the reflection phase according to the rotation angle of the unit geometry is used to achieve 1-bit phase modulation of circular polarization.The active circular polarization reflection array antenna has good axial ratio and gain bandwidth in the center beam radiation,and can also achieve dual circular polarization two-dimensional with wide-angle beam scanning.