Research And Design Of Multi-Band Omni-Directional Antenna

Omni-directional antennas are widely used in mobile communication or one-to-many communication.In order to meet the growing needs of wireless communication systems,omnidirectional antennas are developing in the direction of high gain,multiple frequency bands,and miniaturization.According to actual engineering needs,this paper studies and designs multi-band coaxial omnidirectional antennas.The main work is as follows:1.Three-port multi-band coaxial omnidirectional antenna design.In order to reduce the horizontal size of the antenna system,three antenna units of different frequency bands are placed in a coaxial collinear manner,from top to bottom,followed by L-band high-band antennas,L-band low-band antennas,and UHF-band antennas.Frequency band omnidirectional antenna.According to the index requirements of the L-band two-band antenna,it is proposed to use a microstrip coaxial collinear array to achieve high-frequency omni-directional high gain,and use the sleeve double cone to cover its low-frequency band.A full-wave dipole antenna is used to achieve the high gain requirements of the UHF frequency band.The test results show that the performance of each frequency band of the antenna meets the design requirements.2.Coaxial integrated design of single-port multi-band omni-directional antenna.In order to realize single-port antenna feeding,based on the above-mentioned antenna unit research,two duplexers are used in series to realize three-band inter-frequency combining.First,through the duplexer 1 between the microstrip coaxial collinear array antenna and the biconical antenna,the two frequency bands are combined in different frequencies,and the feeder is passed down through the biconical antenna.Then,the diplexer 2 located between the two antennas below realizes the inter-frequency combining of the three frequency bands,and then extends the total feeder line to the bottom of the antenna to realize single-port feeding.Finally,the designed two duplexers are assembled on the antenna to realize the coaxial integration of the antenna,and the magnetic ring loading technology is used to reduce the influence of the coupling between the feeders on the performance of the antenna.The antenna prototype was tested as a whole,and the test results showed that its performance and size met the design requirements.