Design Of Broadband Low Sidelobes Circularly Polarized Array Antenna

With the rapid development of today's wireless communication technology,circularly polarized antennas are widely used in wireless communication systems such as GPS,WIFI,and RFID due to their good anti-interference ability.Among many types of antennas,microstrip antennas are easier to achieve circular polarization,and they are favored by users because of their small size,light weight low cost,and easy integration.In this paper,a circularly polarized array antenna with low profile,high sain,wideband and low side lobes is designed based on the theory of microstrip array antenna.This paper first investigates the research progress of microstrip antennas at home and abroad,mainly introduces the technology of achieving circular polarization,wideband and low side lobes.Then the basic theory of microstrip antennas is studied,including the basic parameters of the antenna,the radiation mechanism,and the circular polarization feeding method.The principles of vrarious periodic metafaces and their extended antenna bandwidth are briefly introduced.Based on the above research.Two microstrip unit antennas were then designed and their performance optimized to facilitate subsequent high performance array antenna with low return loss and low axial ratio.This paper discusses the theory of array antennas in detail,and the field pattern multiplication theorem,the analysis of the array factor to suppress grating lobes,and the feeding principle of-the circular sequential rotation are mainly derived.Also studied various pattern synthesis algorithms to reduce the sidelobe level,and explore the binomial algorithm and the Dolph-Chebyshev algorithm.Based on the above theory,a 4×2 wideband,low sidelobes,circularly polarized array antenna design scheme is proposed and the antenna synthesis tool was used to verify the correctness of the design.Finally,various feeding networks of array antennas are studied and a four-way splitter is designed and applied to circularly polarized array antennas.The simulation results show that the impedance bandwidth reaches 48%,the axial ratio bandwidth reaches 19%,the left sidelobe level of the H-plane pattern is-20.7dB.and the right-16.9dB.