Research Of Omnidirectional Circularly Polarized Antenna

Omnidirectional circularly polarized antennas are used commonly in modern wireless communication due to their CP property and omnidirectional radiation patterns.Circularly polarized radiation can inhibit the rain,fog interference and multi-path reflection.Meanwhile,the omnidirectional antennas can provide more signal coverage than the traditional directional antenna.Omnidirectional circular polarized antennas are widely used in remote sensing and telemetry,space vehicles(aircraft,missiles,rockets,etc.),radio and television systems,satellite positioning and other aspects.Global Navigation Satellite System(GNSS)has the property of fast response,high efficiency,accurate positioning and other characteristics,and has been widely used in people's daily lives.In order to improve the coverage area of the satellite navigation antenna,the omnidirectional circularly polarized antenna is in great demand.In view of the current situation,the main problem restricting the application of such antennas is that their impedance bandwidth and AR bandwidth is too narrow.It is foreseeable that miniaturized broadband omnidirectional circularly polarized printed antennas will play an indispensable role in future wireless communications.In this paper,the background and significance of omnidirectional circular polarization are introduced.The development trend and the problems of omnidirectional circularly polarized antenna are analyzed.Some related research status of omnidirectional circular polarization antenna are summarized.The research work of this paper revolves around the design of omnidirectional circular polarized antenna,and the research results are innovative and have some significance in engineering practice.The innovation results of this paper are as follows:An omnidirectional circularly polarized antenna based on monopole and extended curved branches is designed.The simulation and experimental results show that the antenna can obtain good omnidirectional circular polarization radiation.With a size of 0.24?0*0.24?0*0.12 ?0,the antenna exhibits a-10-dB impedance bandwidth of 4.4% and a 3-dB axial-ratio(AR)bandwidth of 6.4% in the horizontal plane.The structure of the antenna is simple and compact,and can meet small size requirements for special occasions.An omnidirectional circular polarization antenna based on a crossed dipole is designed.The antenna consists of four crossed dipoles and a feed network.The horizontal part and vertical part of the crossed dipoles control corresponding part of polarized electric field.The principle of omnidirectional circular polarization of the antenna is studied.The structure has the advantages of simple structure,good omnidirectional and wide bandwidth.The antenna has a 10-dB return loss bandwidth and a 3-dB ratio bandwidth of 28.9% and 17.9%,respectivelyAn omnidirectional circularly polarized antenna based on a bended dipole is designed.By bending the dipole,the horizontal part and vertical part of the bended dipoles control the corresponding part of polarized electric field.We can calculate the horizontal and vertical polarized electric field through current distribution and 90 ° phase difference principle.Then a compact and wideband omnidirectional circular polarized antenna can be obtained.With a size of 0.43?0*0.43?0*0.28?0,the antenna exhibits a-10-dB impedance bandwidth of 38.7% and a 3-d B axial-ratio(AR)bandwidth of 36.5% in the horizontal plane.