| With the development of reflector antennas toward high gain and narrow beam direction,higher requirements are placed on the structural accuracy of the antenna working state.The reflector antenna with cover is often affected by wind load,damp heat load,vibration load,etc.during operation.These loads will deform the reflector antenna structure and change the electrical parameters of the radome material,resulting in the far field of the antenna.The electromagnetic performance is attenuated.When the antenna is subjected to mechanical load,the antenna structure will be deformed,and some components will be displaced,which affects the accuracy of the overall structure.When the antenna is subjected to humidity and heat load,it mainly affects the relative permittivity of the radome material,attenuates the transmittance of the radome,thereby affecting the electromagnetic performance of the antenna.Therefore,this thesis takes the Cassegrain antenna as the object to study the influence of the above-mentioned environmental factors on the electromagnetic performance of the antenna.The main research work of this thesis is as follows:(1)A method for modeling electromechanical coupling of reflector antennas based on eigenorthogonal decomposition is proposed.The process of establishing the parametric reduced-order model is briefly described,and the three-dimensional model of the reflector antenna is established and the mechanical analysis and electromagnetic analysis are carried out.Finally,the reduced-order model of the displacement size of the antenna component and the electromagnetic response of the antenna is established.Comparing the prediction results of the reduced-order model with the simulation results of the electromagnetic software,the coincidence of the two is good.Using the reduced-order model instead of the electromagnetic simulation software to calculate the antenna pattern can save a lot of software simulation time.(2)Aiming at the problem that the hooded reflector antenna is affected by factors such as precipitation and high temperature during operation,the evolution of the electrical performance of the hooded reflector antenna under humid heat load is analyzed.According to the effective medium theory,an approximate calculation equation of the dielectric constant of the radome material was deduced.The immersion experiment of the radome material sample was designed and implemented,and the accuracy of the derived approximate equation was verified according to the experimental data.Finally,according to the influence of temperature and humidity on the dielectric constant of the radome material,the evolution curves of the gain and sidelobe level of the radome reflector antenna with the moisture content and temperature of the radome material are obtained.These conclusions have reference significance for engineering applications.(3)The evolution of the electrical properties of the shrouded reflector antenna under vibration loads is analyzed.According to the dynamic differential equation,a method for generating random samples of the antenna node displacement is deduced,and then the mathematical model of the influence of the antenna deformation on the electromagnetic performance of the antenna is obtained.The finite element model of the reflector antenna with cover is established,and the accuracy of the finite element model is proved by comparing the natural frequency of the experiment and the simulation of the finite element model.Finally,a vibration load is applied to the antenna honeycomb material through experiments,the elastic modulus of the material after vibration is substituted into the antenna mechanical model,and the deformed antenna obtained by the vibration simulation is imported into the electromagnetic software for simulation,and the evolution of the electrical performance of the antenna by the vibration load is obtained.(4)An analytical interface for the electromechanical coupling of reflector antennas is developed.The software system embeds software such as ANSYS Workbench into the analysis interface,and uses buttons to control the calling of the software.The antenna model after deformation under load is obtained through simulation calculation,and the electrical performance analysis of the antenna after deformation is realized through the LUA script of FEKO software.Finally,the simulation calculation of the second chapter of this paper is carried out,and the results of the second chapter are compared. |
PDF Full Text Request