Research On Metasurface Circularly Polarized Antenna

With the development of information era,various antennas with specific performance have been widely used in communication,radar,remote sensing and other fields.Among them,because the circularly polarized electromagnetic wave has small propagation attenuation in the atmosphere,strong penetration ability,and is not affected by the Faraday effect generated by the earth’s magnetic field,the circularly polarized antenna has significant advantages in long-distance communication and anti-interference.At present,improving the performance of circularly polarized antenna is one of the research hotspots in this field.However,how to balance the performance of circularly polarized antenna and design an antenna suitable for various occasions has become a challenging problem.In recent years,with the development and breakthrough of metamaterial theory,two-dimensional metamaterials,namely metasurfaces,have been more and more widely used in antenna design due to their unique advantages.The circularly polarized radiation realized by loading a metasurface can improve the performance of the antenna,such as bandwidth,gain,etc.At the same time,it can also make the antenna structure more compact,which is beneficial to the miniaturization design of the antenna.Based on the higher requirements of 5G(5th-Generation)communication technology for antenna performance and the defects of traditional circularly polarized antenna,this thesis conducts a series of studies on circularly polarized antenna based on metasurface structure.The main work can be summarized as follows:1.Research on circularly polarized antenna element based on metasurface structure: A circularly polarized antenna with a center frequency of 30 GHz,a relative axial ratio bandwidth of 33%,and a maximum gain of 9.9dB is designed by loading a polarization conversion metasurface on the linearly polarized slot antenna.Finally,the effects of incident angle,metasurface element spacing and dielectric layer thickness on the performance of circularly polarized antenna are analyzed,and the direction of antenna parameter optimization is provided.2.Research on circularly polarized antenna array based on metasurface structure:A 1×8 linear array is constructed on the basis of the above metasurface circularly polarized antenna element,the performance change of one-dimensional array antenna is studied from two aspects of phase control and amplitude weighting.Then,two kinds of high-gain circularly polarized planar array antennas based on metasurface structure are proposed.H-type SIW(Substrate Integrated Waveguide)power divider is used to feed the array,and the maximum gains of 20.6dB and 26.7dB are achieved for the two arrays respectively.Finally,the 4×4 array antenna is fabricated and measured.The actually measured-10 dB impedance bandwidth is 12.5%,3dB axial ratio bandwidth is 30.7%,and the maximum gain is 20.9dB.