Research On Thermal Adaptability Simulation Of Airborne Active Phased Array Antenna And Its Verification And Validation Method

With the recent development of active phased array antennas(APAA)in high integration,the environmental adaptability of APAA faces significant challenges.Due to the advantages of high efficiency,low cost,and high feasibility throughout the product design cycle,simulation is more and more widely used in environmental adaptability assessment and optimization.Because of the high thermal power of modern APAA and the extremely limited space of the airborne platform,thermal design of airborne APAA may be the most important and difficult issue in the environmental adaptability design.At the same time,the simulation-based thermal adaptability assessment of airborne APAA is also very difficult because of the complex heat generation and transport process as well as the multiple influence paths on antenna performance.In order to improve the accuracy and efficiency of such simulation so as to improve thermal adaptation of APAAs,the simulation and verification/validation methods are studied in this thesis.The main work is summarized as follows:Firstly,the characteristics of the thermal adaptability of the APAA antenna are analyzed in detail.Combined with the composition principle of the APAA antenna and the characteristics of the airborne platform,the thermal adaptability of the APAA antenna is analyzed from the perspectives of heat source,heat transfer path and environmental thermal characteristics.The effect analysis of heat on the APAA antenna is based on the physical mechanism.Secondly,the general process of phased array antenna design and the conventional simulation methods are summarized.A microstrip antenna array is designed in detail,and the design results are be used as the basic object of subsequent thermal adaptability simulation analysis.The electromagnetic simulation results show that the microstrip antenna has excellent electromagnetic performance.The heat flow simulation results show that the cold plate meets the requirements of heat dissipation and pressure drop.Thirdly,based on the established antenna model and the characteristics of thermal adaptability,the research on thermal adaptability simulation method is carried out.In order to ensure the accuracy of the simulation,the different working states of the antenna are considered in the simulation model.The heat source power,ambient temperature and heat exchange conditions are set.The influence of thermal deformation on antenna performance is investigated by "thermal-mechanical-electromagnetic" coupling simulation.In order to improve the thermal adaptability simulation efficiency,the main factors in the simulation process and the influence on the results are analyzed.The results show that the change of the dielectric constant of the dielectric plate at different temperatures,the change of the thermal physical parameters of the cooling medium and the thermal deformation of the front surface are the main factors that should be considered in the thermal adaptability simulation.The relative permittivity change caused by the temperature rise will lead to the decrease of the antenna gain and the frequency shift while the thermal deformation reduces the antenna gain and the sidelobe electric power.Finally,combined with the characteristics of antenna thermal adaptability simulation and the principle of VV?A method,the verification and validation method of airborne phased array antenna thermal adaptability simulation are discussed and analyzed.The grid convergence index method is used to evaluate the grid error in the antenna heat flow simulation and structural simulation.Based on the sensitivity coefficient propagation method,the validation variables and validation general processes in the antenna heat flow,electromagnetic simulation and structural simulation are summarized.