Research On Triband Broadband Antenna For Mobile Communication System

With the rapid increase of wireless communication data,the demand for broadband antenna in mobile communication system is increasing,and at the same time,the single narrowband antenna can not meet the demand.In November 2017,China’s Ministry of industry and information technology stipulated 3.3～3.6 GHz and4.8～5 GHz as China’s 5G mobile communication band,indicating that the commercial application of 5G technology is gradually realized.China’s wireless communication technology has experienced the gradual development process from2G,3G to 4G.5G network technology,as an advanced information transmission technology,it will become the first of the mainstream application technologies in the future wireless mobile communication field.As everyone knows,the development of mobile communication technology is a process of step-by-step progress,from simple to deep progress,and seeking progress in stability.In the future,2G,3G,4G,5G mobile communication systems will coexist.Therefore,it is urgent to study the theory and technology of multi frequency broadband antenna in academic circles.In this paper,for mobile communication system,a single polarization triband broadband antenna and a dual polarization triband broadband antenna are designed.The former realizes the full band coverage of 2G,3G,4G and 5G communication,while the latter realizes the full band coverage of 2G,3G and 4G communication and partial band coverage of 5G communication.The main work of this paper is as follows:（1）A monopolarized triband broadband antenna for mobile communication system is proposed.The main radiation structure of the antenna is composed of a pair of stepped dipoles loaded with branches,which are fed by parallel two-wire.The parasitic stepped dipoles are loaded above the main radiation structure to couple part of the energy of the main radiation structure to the parasitic structure,so as to achieve high gain coverage in 5G band.The test results show that the impedance matching bandwidth of|S₁₁|less than-10 d B are 0.681～0.96 GHz,1.6～2.73 GHz and 3.14～5 GHz,covering 0.69～0.96 GHz,1.71～2.69 GHz and 3.3～5 GHz,the relative bandwidth is 33.9%,52.2%and 45.7%respectively,the peak gain is 7 d Bi,9.5 d Bi and 10.8 d Bi respectively,and it has good radiation performance.（2）A dual-polarized triband broadband antenna for mobile communication system is proposed.The main radiation structure of the antenna consist of a bow dipole and a folded ring-shaped metal ring loaded with branches.The parasitic patch is loaded on the top of the main radiation structure to improve the impedance matching in intermediate frequency band of the antenna.The two ports adopt（38）-type microstrip coupling feeding structure with different heights,which effectively avoids the cross of two port feeders between two polarization ports and improves the isolation between the ports.The simulation results show that the impedance matching bandwidths of|S₁₁|and|S₂₂|less than-10 d B cover 0.72～0.96GHz,1.71～2.69 GHz and 3.3～3.8 GHz,and the relative bandwidths are 28.6%,44.5%and 14.1%respectively.The port isolation of 28 d B and the port one’s average gain of 6 d Bi,7 d Bi and 7.6 d Bi are achieved respectively in the three frequency bands mentioned above.