| As the transmitting and receiving device of electromagnetic wave,antenna has an irreplaceable role in wireless communication and radar.With the development of wireless communication and electromagnetism,the advantages of circularly polarized antenna also appear,the original polarized wave can absorb any polarized incoming wave,and the radiation wave can also be received by any polarized antenna,and the anti-fog ability and anti-multipath reflection ability of circularly polarized antenna are especially strong,so the application of circularly polarized antenna is also especially wide in recent years.The first chapter describes the research background of broadband microstrip antennas,wide-beam microstrip antennas,conformal antennas and phase center stability of antennas and the current status of research at home and abroad.The second chapter introduces the microstrip antenna,including the principle of partial design of microstrip antenna,the principle of spreading bandwidth and beamwidth;and the principle of microstrip common antenna as well as focusing on the implementation method of microstrip patch antenna;the antenna design that can be taken to improve the phase center stability is introduced.The third chapter section designs a single point feed antenna,the design principle is the use of coaxial line and semi-circular phase shift ring to achieve 0°,90°,180° and 270° phase difference,and gives a detailed structural design,electromagnetic simulation software analysis,single point feed antenna can cover GPS L1 and BD B1 two navigation bands,the feed method effectively avoids the use of two point feed caused by beam shift,at the same time In order to improve the beam width,the folded conductive wall is introduced,and the beam is widened by using the principle of Yagi antenna guide,after the electromagnetic simulation software simulation analysis,the feeding method widens the circularly polarized beam width relative to the surrounding method.At the same time,because the antenna radiating piece is printed with PCB board,using workbanch simulation,the reliability of the antenna is analyzed,the single point feed antenna has high frequency of resonance and strong structural reliability.A conformal antenna is designed in section IV.Due to the need for conformal,the antenna uses a microstrip antenna side feed.The antenna uses a dielectric sheet which is easy to be conformal,and the power divider and 90° phase generator feed the antenna to increase the axial ratio bandwidth of the antenna,and the antenna unit gain is higher than 4d Bi.after the four units are grouped together and conformal with the cylindrical surface,the antenna has a higher gain in the required direction while satisfying the antenna axial ratio less than 3d B in the four required directions.Chapter 5 section designed a choke antenna,the antenna radiation piece printed on the PCB board,reduce the processing cost,at the same time the antenna adopts the form of cross oscillator,effectively spread the working bandwidth,after simulation analysis,the antenna works at 1.1GHz-1.7GHz,the designed choke can spread the beamwidth of different frequency bands,the antenna gain full band is greater than 6d Bi,circular polarization beamwidth is greater than ±50°.In order to increase the structural strength,the antenna is fixed on the choke using non-metallic studs,and after workbanch analysis,the modal first order is greater than 300 Hz,and the structural stability is strong.Due to the antenna working band is wide,the feed network is consistent with that of chapter 4 section,and the simulation after the combination of feed network and antenna found that the phase center stability is strong. |
PDF Full Text Request