Research On Broadband Circularly Polarized Antenna Based On Artificial Meta-structure

With the development of radio frequency communication,there is an increasing demand on the stability and reliability of the communication system.As the terminal of communication systems,the performance of antenna affects the working state of the entire system directly,such as bit error rate,transmission distance,position accuracy and so on.Microstrip antennas have gained extensive attention in wireless communication research due to their small size,low profile,easy integration,and low price.In this paper,based on the current hot application of microstrip antennas,we studied the wideband and circular polarization techniques to improve the antenna performance.The main work of this paper is as follows:1.Based on the shortcoming of narrow bandwidth of microstrip antenna,we studied the bandwidth enhancement method.By using artificial superstructure,the bandwidth is enhanced by 100%,which can effectively solve the narrow bandwidth problem caused by the high Q value of the microstrip antenna.2.Based on the requirements of circular polarization in mobile communication and satellite communication,a wideband circularly polarized microstrip antenna with coplanar waveguide is studied and designed.The coplanar waveguide feeding structure and microstrip slot antenna are combined together to realize the impedance bandwidth of 4 GHz and the axial ratio bandwidth of 1.0 GHz.The antenna not only has the characteristics of low profile and wide bandwidth,but also has a bidirectional radiation pattern in the circular polarization band,which can improve the flexibility of the antenna application.3.Based on the demand for spectrum resources in the field of wireless communication,a circularly polarized antenna array for generating vortex waves is proposed.By controlling the rotation direction of the array unit and the setting of the feed amplitude and phase,and constructing the vortex wave test system,it is experimentally proved that the antenna array can generate vortex electromagnetic waves in a wide frequency band.These beams can be transmitted on the same frequency,which used to send multi-path of information simultaneously.It can improve the system capacity greatly,which has been used in the field of optical frequency bands and radio frequency communications.