| The working environment of the spaceborne phased array antenna is very special.The spaceborne phased array antenna with satellite in orbit is heated by the periodic space heat flow dominated by solar radiation and cooled by the low temperature heat sink in the cosmic space.As a result,the temperature of the spaceborne active phased array antenna fluctuates violently and generates a large temperature gradient,which leads to the deterioration of the antenna’s electrical performance.The coupled structural-electromagnetic-thermal problem of spaceborne phased array antennas caused by space heat flow and internal temperature load has become an urgent problem to be solved in the development of spaceborne phased array antennas.Therefore,theoretical calculation,numerical simulation and optimization design are used to research on the prediction method of extreme working conditions of sunsynchronous orbit,the structural-electromagnetic-thermal coupling analysis of spaceborne phased array antenna and the thermal control optimization design of spaceborne phased array antenna.The major contents can be summarized as follows.(1)The sun-synchronous orbit is studied in this thesis.First,the sun and earth vectors are determined in the satellite body coordinate system.The calculation method of solar illumination angle of sun-synchronous orbit plane and orbital shadow are introduced.The occlusion calculation method for satellite components are studied.The theory and method for predicting the extreme working conditions of the sun-synchronous orbit are proposed,which comprehensively consider the factors of space heat flux,model occlusion and orbit shadow.In addition,three analytical models including a simplified envelope model of a spaceborne phased array antenna are used to verify the extreme working condition prediction method.(2)A spaceborne array antenna is analyzed by the coupled structural-electromagneticthermal analysis method.The thermal and structural analysis model of the spaceborne phased array antenna is simplified and established.The temperature at the initial thermal control coating and the final thermal control coating under extreme working conditions and typical working conditions are calculated.Then,the temperature variation in the antenna orbital period is analyzed and the location of the extreme temperature is determined.By mapping the node temperature loads to the structural analysis model,the deformation and stress of the antenna under extreme and typical working conditions are calculated.The electromechanical coupling model of the triangular grid array is established,and the changes of the electrical performance parameters of the antenna before and after deformation are analyzed.In addition,the changes in the electrical performance of the antenna under different amplitude errors and extreme temperature load distributions in the extreme deformation mode are further explored.(3)A thermal control optimization model with the objective of the antenna surface accuracy(minimum weighted root mean square value)under multiple working conditions is established.And the optimization variables are the solar absorptivity and surface emissivity of the thermal control coating.Taking a spaceborne phased array antenna as an example,the thermal control optimization design is carried out based on the structural-electromagneticthermal coupling analysis.The optimization results show that the antenna surface accuracy under multiple working conditions is significantly improved(the weighted root mean square value decreases by 58.1%)after the thermal control optimization design.By means of thermal control optimization,the influence of temperature load on the antenna performance is reduced,and the electrical performance of the spaceborne phased array antenna under multiple working conditions is guaranteed. |
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