Multi-Field Coupling Analysis And High Stability Index Assignment Of Large Spaceborne SAR Antenna

With the further exploration of high resolution imaging technology,Synthetic Aperture Radar(SAR)satel ite is moving towards the direction of the multi-mode,high resolution and high image quality.As the moving and imaging process of the satel ite,SAR antenna is in a complex environment with multiple physical fields.And it is affected by many kinds of disturbing sources at the same time,which affects the pointing accuracy and imaging quality seriously.Therefore,the research contents of this paper are of great significance to improve the design of spaceborne SAR antenna,reduce the error of pointing accuracy and improve the image quality of spaceborne SAR antenna.The main object of this paper is the large space borne SAR antenna.In this paper,firstly,the imaging principle and field coupling parameters of the space borne SAR antenna are studied.Then the possible errors in the antenna structure are studied.According to the mathematical model of the electromagnetic field in the far field of the antenna caliber,the ideal antenna pattern is drawn and the possible structural errors of the antenna are introduced into the ideal antenna pattern.As a result,the electro-mechanical field coupling model of the antenna is established.Secondly,the variable temperature field of the space borne SAR antenna is studied during the orbit period.The influence of the temperature field on the antenna structure is simulated by applying the equivalent load on the antenna structure.And the deformation of the antenna structure under the equivalent load of the temperature field is calculated by using the finite element model of the SAR antenna.At the same time,the deformation results are introduced into electro-mechanical two coupling model,with the result that the electro-mechanical-temperature multi-field coupling model is established.Finally,through the study of the main vibration source disturbance and the definition of high stability index assignment in the satel ite SAR antenna system,and combined with the index al ocation theory of space borne antenna,a multifactorial quantification model for pointing accuracy of space borne SAR antennas is proposed.According to the multifactorial quantification model,the pointing accuracy of antenna under disturbance sources are calculated by combining with the concrete simulation examples,and the specific index al ocation steps and examples are given.The result further verifies the validity of the multifactorial quantification model.From above research,following conclusions can be drawn that the moving and imaging process of the space borne SAR antenna is affected by many physical fields,which contain machine,electrical and thermal.And the electro-mechanical two coupled model is the basis and key of the analysis of the multi-field coupling model.The influence of the disturbance source under the zero mean and unit variance on the accuracy of the antenna is related to the location of the satel ite.What’s more,the closer the perturbation source is to the spaceborne antenna structure,the greater the degree of impact to the accuracy.The multifactorial quantification model of the index assignment can effectively calculate the influence degree of each disturbance source on the antenna pointing accuracy,which will not lay theoretical foundation for the error quantization and the optimal control of the pointing precision,but also provide a new idea for the technical staff in antenna system design.At the same time,the above facts indicate that this work has a certain theoretical significance of the study and application value in the field of practical engineering.