| As a most important part in the mobile communication system,the base station antenna is the core equipment to make mobile communication network exist in the larger area.At present,with the rapid development of electronic technology,the gradual maturity of the 3G and 4G network,and the coming achievement of the 5G network prediction,mobile communication system also put forward stricter requirements for the performance of the base station antenna.Nowadays,the development trend of the base station antenna is moving towards the direction of broadband and miniaturization of antenna.Micro-strip antenna has the advantages of light weight,small size,integration and easy processing,and it has become the first choice for the design of base station antenna.In 2006,according to the complementary antenna design thought put forward by Clavin,professor Luk design a new broadband directional antenna unit,called it magneto-electric dipole antenna.On the basis of the antenna unit,he experimented a large number of research,exploration and design to meet the specific requirements of mobile communication systems,especially reducing the antenna profile and expanding its bandwidth.A patch antenna is used as an electric dipole and a patch shaped triangular loop antenna is used as a magnetic dipole.Luk combined them to achieve a low-profile wideband complementary dipole antenna.The antenna not only had a 0.16? height and simple structure,but also achieved a relative impedance bandwidth of 44.3%(VSWR?2),stable gain antenna,stable radiation pattern,low back radiation and low cross polarization over the operating frequencies.In this paper,a detailed study of the complementary dipole antenna unit is firstly presented.Then on the basis of the research achievements and the related literature,two slotted magneto-electric dipole antenna unit are designed though improving antenna.They are called single-slot magneto-electric dipole antenna unit and dual-slot magneto-electric dipole antenna unit.Single-slot magneto-electric dipole antenna unit is operating in the frequency range of 1.9GHz-2.75 GHz.The antenna can achieve an impedance bandwidth of 36.6%(VSWR ?2),stable antenna gain up to the maximum 9.1d B.In addition,the antenna has a stable radiation pattern,low back radiation and low cross polarization over the operating frequencies.More importantly,compared with the magneto-electric dipole antenna offered by Luk,the volume of single-slot electromagnetic dipole antenna is reduced by 24.46%.In order to make the antenna unit smaller,this paper also design another new antenna unit,dual-slot magneto-electric dipole antenna unit.The antenna also has a wide relative impedance bandwidth of 35.1%(VSWR ?2)and stable radiation pattern,the overall profile of the antenna reduced by 28.54%,but the antenna gain over the operating frequencies is not very stable compared with the single-slot magneto-electric dipole antenna unit.In addition to the improvement of the antenna unit,the antenna array is also studied simply in this paper.Firstly,the linear array is designed by using the complementary magneto-electric dipole antenna as the array element,then the paper simulates the array and study its characteristics.By comparing the simulation results of two kinds of improved antenna units,it is found that the dual-slot magneto-electric dipole antenna unit is not suitable for array design,so taking eight-element linear array composed of the complementary magneto-electric dipole antennas as a reference,this paper mainly studies eight-element linear array design composed of the single-slot magneto-electric dipole antenna units,and optimize the size parameters of the linear array at different spacing.On the basis of parameter optimization,the eight-element linear array is modeled and simulated.The simulation results show that the design of the single-slot magneto-electric dipole antenna unit in this paper has a wide impedance bandwidth,stable gain and stable radiation characteristics.Moreover,the antenna profile is greatly reduced,which makes it more convenient for array design.In order to make the linear array to meet the more and more strict requirements of base station antenna,this paper finally studied simple beamforming of the array to satisfy cosecant function through the study of Woodward-Lawson sampling method. |
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