Influence of sunlight on the surface error of a large antenna reflector and its correction method
Large antennas are characterized by large apertures,high precision,complex structures,and extended outdoor operation.The effect of a non-uniform and real-time thermal deformation error of an antenna reflector caused by sunlight on the electrical performance of an antenna is considerable.Herein,the Jingdong 120-m antenna is considered the research object.The finite element method is employed for determining the non-uniform temperature distribution and the law for its variation for the antenna reflector under different observation attitudes and sunlight environments.The evolution law of the main reflector surface shape under the influence of real-time varying sunlight is discussed,and the real-time error of the non-uniform thermal deformation of the surface shape is compensated.The findings reveal that due to the influence of the sunrise in the east and the sunset in the west,changing the observation azimuth and elevation angle of the antenna can affect the temperature experienced by the reflector by 4℃ and 1.5℃,respectively.This indicates that the observation azimuth has a greater effect on the heat experienced by the reflector as compared to the elevation angle under the identical sunlight environment.The thermal deformation of the antenna structure exhibits time variation and non-uniformity throughout the day,and the largest deformation is observed at 14:00.Affected by the annual variation in sunlight,the change in antenna observation azimuth angle will affect the change rule of reflector temperature difference,which increases,decreases and then increases.The standard deviation of temperature at noon in summer is the least(0.1);therefore,the thermal deformation of the reflector increases,decreases and increases again throughout the year.Further,thermal deformation in winter is the highest,reaching 2.6 mm,and the maximum in other seasons is 2 mm,indicating that the sunlight in winter has a considerable thermal effect on the antenna reflector.Based on the variation law of the reflector thermal error,the error coupling principle is introduced to analyze the thermal deformation error of the reflector,and the compensation is realized by the feed adjustment mechanism.The reflector thermal deformation simulation technology and feed compensation method proposed in this paper can provide a theoretical basis and technical support for improving the pointing accuracy of large antennas.
large antennareflectorinsolationthermal deformationerror compensation
万方数据
维普
