Research And Desigin Of Beidou Metasurface Circularly Polarized Dual-band Microstrip Antenna

Beidou navigation system radiates circularly polarized signals with multiple frequency bands signals,the microstrip antenna can better achieve circularly polarization and multi-band.In order to meet the needs of the navigation antenna,the realization of the circularly polarization and dual-band characteristics of microstrip antenna has been studied.The main work contents are as follows:Firstly,a circularly polarized microstrip antenna working in Beidou B1 and B2 dual-band is designed.On the basis of the design of the single-layer radiation patch,the dual-band radiation characteristic is realized by using the stacked structure.The circularly polarized radiation is realized by adding a perturbation element to the two-layer patch,and the miniaturization is realized by different slots on the upper and lower layers.Through simulation optimization,the impedance bandwidths of the two frequency bands are 48.13MHz and 78.22MHz,the VSWR bandwidths are 51.1MHz and 84MHz,and the axial ratio beamwidths are 192° and 228°,respectively.The axial ratio,pattem and gain performance of the antenna are good.Under the same complexity,the impedance bandwidth and circular polarization performance of the antenna are better,and it has a wider axial ratio beam,which is conducive to the acquisition of more positioning information.Secondly,a dual-circularly polarized microstrip antenna for Beidou L and S dual-band is designed.The antenna consists of two layers of square patches stacked to achieve dual-band radiation.By cutting sectors of different sizes at the diagonal positions of the two layers.the Lband antenna achieves left-handed circularly polarized radiation,and the S-band antenna achieves right-handed circularly polarized radiation.Through simulation optimization,the impedance bandwidths of the two frequency bands are 96.6MHz and 147MHz,respectively.the VSWR bandwidths are 92.4MHz and 100.6MHz,and the axial ratio beamwidths are 140°and 120°,respectively.Thirdly,in order to improve the gain and bandwidth of the antenna,a metasurface structure is designed.The metasurface antenna utilizes the periodic structure characteristics of the metasurface to improve the standing wave ratio bandwidth,axial ratio,pattern of the circularly polarized dual-band antenna.Compared with the original antenna,the impedance bandwidth of the metasurface-loaded antenna in the low frequency band increases by 35.7MHz,and the standing wave ratio bandwidth is increased by 33.6MHz,the peak gain is increased by 3.05dBi,and the circular polarization performance is better,and the performance of the antenna in the high frequency band remains good.By loading a circularly polarized metasurface onto the microstrip antenna,the microstrip antenna can be converted from linearly polarized radiation to circularly polarized radiation.The working center frequency is 1.575GHz and the impedance bandwidth is 74.1MHz.Good circular polarization characteristics can be achieved in the working frequency band.The designed circularly polarized dual-band antenna has simple structure and good performance.The design method of the dual-band circularly polarized antenna loaded with metasurface provides a feasible design scheme for the research of Beidou navigation terminal antenna.