| Based on the large-scale application of fifth-generation(5G)mobile communication system technology,research on massive MIMO technology has always been the focus of the antenna field.Massive MIMO technology turns the previous beamforming into a more precise 3D beamforming,increasing the data transmission rate and capacity for all users and reducing interference to neighboring cells.The realization of a massive MIMO system requires a larger-scale antenna base station,which requires a more compact distance between antenna units.The reduction of the distance between the antenna elements makes the coupling between the elements more and more intense,which makes the radiation performance of the antenna far from the required index.Therefore,reducing the mutual coupling of the antenna elements has become a research hotspot nowadays.The thesis mainly studies the miniaturization and decoupling of dual-polarized array antennas.The main contents are as follows:First of all,the paper investigates the research on decoupling of array antennas,expounds the necessity of the research content in this paper,and summarizes the development status and trends of various decoupling structures by domestic and foreign scholars in recent years.Then,the basic theory and mutual coupling analysis method of the array antenna are introduced,which lays the foundation for the following simulation design.Secondly,on the basis of the previous investigation and theoretical analysis,a three-element antenna array loaded with metal wall structure and shifting network is proposed.Firstly,a dual-polarized dipole antenna operating at 5.15～5.85 GHz is designed as an array radiating element,and a microstrip balun is used for coupling and feeding.The three crossed dipole antennas are combined together by a power splitter to form a three-in-one antenna array,and then the metal wall structure is loaded and moved to the network for hybrid decoupling.By comparing the current distribution on the antenna surface before and after loading the metal wall structure,the decoupling effect of the metal wall structure on the array antenna is analyzed.The antenna is further decoupled using a phase-shifted power division network.The results show that the coupling between the three-in-one array antennas is reduced by more than 12 d B,the VSWR is less than 1.5,and the gain is 12 d Bi,which is in line with the design.Require.Finally,the simulation model is processed and tested,and the decoupling effect of the metal wall structure and the moving network is verified.Finally,the decoupling study of large-scale antenna arrays by metasurface structures and spacers is carried out.Firstly,a dual-polarized dipole antenna operating at 2.5～2.69 GHz is designed,which is miniaturized by bending the dipole arm and slotting it.In order to facilitate beam steering,two miniaturized dual-polarized antennas are connected to form a two-in-one antenna sub-array through a power divider.A spacer with a height of 13mm(slightly less than 1/8 λ)is added around the two-in-one antenna sub-array to reduce the isolation between the antennas by 2.5 d B.On this basis,the sub-arrays are formed into 2×4array antennas with a horizontal spacing of 48 mm(about 0.42 λ)and a vertical spacing of78 mm(about 0.68 λ).By covering the metasurface structure above the array,the co-polarity isolation of the array is reduced to below 24 d B,and the heteropolarization isolation is reduced to below 27 d B.Finally,it was expanded into an 8×8 array antenna and processed and tested.The results prove that the spacer and metasurface reduce the coupling degree between the array elements without causing too much influence on the pattern. |
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