Research On Massive MIMO Array Antenna Applied In 6G

With the iterative and continuous advancement of mobile communication technology,in recent years,base stations and mobile terminal equipment have gradually evolved from 4G,5G to 6G,which has mainly brought about two major development trends: On the one hand,the improvement of communication quality and transmission rate will lead to a surge in demand for channel capacity and spectrum efficiency,which makes the number of base station antenna units exponentially increase.On the other hand,under the development trend of miniaturization and integration,more and more antennas are integrated into a smaller space.The physical size of the antenna is compressed,and the problem of electromagnetic interference between antennas will become more serious.Therefore,it is of great significance to study the antenna problem in Massive Multiple Input Multiple Output(MMIMO)systems.First,a dual-polarized base station antenna unit operating at 6 GHz-8 GHz is designed.By bending the radiating arm and changing the current path to miniaturize,the aperture size of0.3?×0.3? is realized,and the microstrip-slit coupling feed structure is adjusted to increase the resonance point,and the relative bandwidth of 28% is realized.The base station antenna unit has a small port size,which is convenient for miniaturization and integration;has a wide working bandwidth to meet the needs of large-capacity communication;and has a stable lobe width and radiation gain in the entire working frequency band,which is the basis of the MMIMO array.Then,on this basis,the broadband miniaturized base station antenna unit is arrayed.In order to take into account the integration and mutual coupling,a staggered array is used to form an array.The coupling is classified according to the polarization type and position relationship.The coupling can be divided into five types: adjacent E-plane coupling,adjacent H-plane coupling,interphase E-plane coupling,interphase H-plane coupling,and orthogonal polarization coupling.For different types of coupling,a combined decoupling scheme including an array decoupling plane,a dielectric coating and a band-stop frequency selective surface isolation network is designed.Applying this scheme to 3×3 arrays,4×4arrays,and larger-scale n×n arrays for analysis,Various types of coupling in the M-MIMO array can be reduced by 5-15 d B,and the isolation between any two ports can be increased to more than 25 d B.And then,the significance of antenna decoupling was studied at the system level.The spatial electric field and total efficiency of the antenna are introduced into the traditional MIMO channel model to modify it,and an M-MIMO channel evaluation model with the characteristics of large number of antennas and close unit spacing is established.The base station antenna array before and after decoupling is substituted into the model as the receiving antenna for calculation and comparison analysis.The results show that the channel capacity after decoupling is increased by about 10% compared with that decoupled,which proves the influence of antenna coupling on the system and the the necessity of decoupling.A channel capacity simulation model was also built in the System VUE software,and simulation calculations were performed.The obtained results further proved that antenna decoupling is of great significance to the improvement of system channel capacity.Finally,the sidelobe optimization of the base station antenna array is studied.Considering the practical application of sub-8 GHz base stations,the upper side lobes and satellite communications should be prevented from interfering with each other.Therefore,based on the genetic algorithm,under the constraints of power loss and beam width,aiming at the sidelobe level in the specified airspace range,the unit spacing and the feed amplitude phase are optimized,an asymmetric pattern with the sidelobe level of the 12-element linear array lower than-38 d B within the specified pitch angle range is realized.In addition,based on the Monte Carlo statistical method,the influence of M-MIMO array feed amplitude error and phase error on the pattern is studied,and the deterioration rule of the error on the average sidelobe of the pattern is found in the large sample random error,and statistics and analysis are carried out.It provides guidance for the design of the actual feeder network and device selection.