Structural Design Analysis And Experimental Study On Massive MIMO Antenna With Low Wind Resistance

With the development of science and technology,mobile communicating technology has evolved into the fifth generation,and 5G base station antennas have widely used.Currently,5G base station antenna is mostly installed on the pole,and the main load it receives is wind load.In order to keep the load on the pole within its bearing range,the size of the antenna array should not be too large,which seriously restricts the increase in the number of antenna elements and affects the performance of the antenna.In this paper,a massive MIMO antenna with low wind resistance was designed and processed.Different from the traditional overall packaging form,it encapsulated each antenna element individually.The main design process and analysis results are as follows:(1)On the premise that the size of the antenna element was determined,the aerodynamic shape of the radome was designed.The resistance coefficients of 7 common shapes were obtained through simulation analysis.It is found that the resistance coefficient of water droplets(streamline shape)is the smallest,which is only 0.082.When the radome is arranged in an array,the influence of the drag coefficient and the windward area on the wind resistance needs to be comprehensively considered.After comparison,a cuboid with pyramid at both ends was used as the preliminary shape scheme of the radome,and it was optimized.The windward area of the optimized shape has not changed,and the drag coefficient is reduced by 16% compared with that before optimization.So the optimized shape was used as the final shape scheme of the radome.(2)Considering the wave-transparent property of the material and processing cost,polylactic acid(PLA)was selected as the material of the radome,and the molding process was fused deposition modeling(FDM).After the electrical property test,it is found that the dielectric constant and loss tangent increase with the increase of the filling rate,indicating that the lower the filling rate,the better the wave-transparent property.After the mechanical property test,it is found that the elastic modulus increases with the increase of the filling rate,and the Poisson’s ratio decreases with the increase of the filling rate,indicating that the higher the filling rate,the better the mechanical properties.The angle of incidence of the radome is in the range of 16°-63°,with an average angle of incidence of 39°.The working frequency band of the antenna is 3.4-3.6GHz,and the center frequency is 3.5GHz.After the wave-transparent property check and the mechanical property check,the radome was finally determined to be a thin-walled structure with a wall thickness of 2mm and the material is PLA with a filling rate of 100%.(3)The structural design of the array antenna was compeleted and the wind resistance analysis was conducted under different windward angles.The results show that when the windward angle is 180°,the wind resistance is the largest,which is 135 N.When the windward angle is 90°,the wind resistance is the smallest,which is 40 N.Compared with the traditional packaging form,the array antenna designed in this paper can effectively reduce the wind resistance.When the windward angle is 0°,the wind resistance is reduced the most by 32%.After static analysis,it is found that at any windward angle,the maximum stress appears on the installation structure,and the maximum deformation appears on the radome on the upper part of the array.The maximum stress is 60.335 MPa,and the maximum deformation is 1.5337 mm,which are both within acceptable limits.After modal analysis,the mode of vibration and natural frequencies of six lowest order modal of the array antenna were obtained.It was found that the first two modes have almost no effect on the electrical performance of the antenna,and the last four modes may have an impact on that of the antenna.(4)The processing and assembly of the array antenna were completed,and the physical model was obtained.The wind tunnel test was carried out on the physical model under different windward angles to measure its drag coefficient and stress distribution,and the causes of errors were analyzed.The experimental results are basically consistent with the simulation results in the trend,which verifies the correctness of the simulation.