Active reflectors are often used to compensate the surface distortion caused by environmental factors that degrade the electromagnetic performance of large high-frequency reflector antennas.This is crucial for maintai...Active reflectors are often used to compensate the surface distortion caused by environmental factors that degrade the electromagnetic performance of large high-frequency reflector antennas.This is crucial for maintaining high gain operation in antennas.A distortion compensation method for the active reflector of a large dual-reflector antenna is proposed.A relationship is established between the surface deformation and the optical path difference for the primary reflector by geometric optics.Subsequently,employing finite element analysis,a polynomial fitting approach is used to describe the impact of adjusting points on the reflector surface based on the coordinates of each node.By standardizing the positions of various panels on the reflector,the fitting ns can be applied to the reflector panels of similar shapes.Then,based on the distribution characteristics of the primary reflector panels,the adjustment equation for the actuators is derived by the influence matrix method.It can be used to determine the adjustment amount of actuators to reduce the rms of the optical path difference.And,the least squares method is employed to resolve the matrix equation.The example of a 110 m aperture dual-reflector antenna is carried out by finite element analysis and the proposed method.The results show that the optical path difference is reduced significantly at various elevation cases,which indicates that the proposed method is effective.展开更多
Obtaining the wind load distribution on the telescope aperture is very important to estimate its influence and reduce the wind disturbance on the telescope system.The aperture of the radio telescope structure can be a...Obtaining the wind load distribution on the telescope aperture is very important to estimate its influence and reduce the wind disturbance on the telescope system.The aperture of the radio telescope structure can be as large as 100 m and therefore,the uniform wind load on the aperture assumption is not suitable for the radio telescope with large aperture.In this paper,a gradient segments superposition method for calculating the wind load has been proposed.The proposed method has been constructed by combining two regional divisions.First,reflecting surface has been evenly divided in the altitudinal direction.Second,the reflecting surface has been divided into several uniform rings assuming that the wind load coefficient on different rings are different.For the 110 m aperture radio telescope,the wind load estimation results differ by 28%.After that,a structural dynamics model of telescope has been established and a fuzzy PID controller has been designed to reduce wind disturbance.The Root Mean Square Error of telescope pointing under wind disturbance has been reduced by 67.8%.It is suggested that the proposed wind load estimation method has lay a solid foundation for the design of the large telescope system under wind disturbance.展开更多
基金funded by the National Natural Science Foundation of China(NSFC,grant Nos.12363011,52275270,and 52275269)Natural Science Foundation of Xinjiang Uygur Autonomous Region(No.2023D01C22)+1 种基金the Tianchi Talents Program of Xinjiang,the National Key Basic Research Program of China(No.2021YFC2203501)the Xinjiang Postdoctoral Foundation。
文摘Active reflectors are often used to compensate the surface distortion caused by environmental factors that degrade the electromagnetic performance of large high-frequency reflector antennas.This is crucial for maintaining high gain operation in antennas.A distortion compensation method for the active reflector of a large dual-reflector antenna is proposed.A relationship is established between the surface deformation and the optical path difference for the primary reflector by geometric optics.Subsequently,employing finite element analysis,a polynomial fitting approach is used to describe the impact of adjusting points on the reflector surface based on the coordinates of each node.By standardizing the positions of various panels on the reflector,the fitting ns can be applied to the reflector panels of similar shapes.Then,based on the distribution characteristics of the primary reflector panels,the adjustment equation for the actuators is derived by the influence matrix method.It can be used to determine the adjustment amount of actuators to reduce the rms of the optical path difference.And,the least squares method is employed to resolve the matrix equation.The example of a 110 m aperture dual-reflector antenna is carried out by finite element analysis and the proposed method.The results show that the optical path difference is reduced significantly at various elevation cases,which indicates that the proposed method is effective.
基金the National Key Research and Development Program of China under No.2021YFC2203600the National Natural Science Foundation of China under Nos.52005377 and 52275268+2 种基金the National Defense Basic Scientific Research Program of China under No.JCKY2021210B007Wuhu and Xidian University Special Fund for Industry-University-Research Cooperation under No.XWYCXY-012021012Youth Innovation Team of Shaanxi Universities under No.201926.
文摘Obtaining the wind load distribution on the telescope aperture is very important to estimate its influence and reduce the wind disturbance on the telescope system.The aperture of the radio telescope structure can be as large as 100 m and therefore,the uniform wind load on the aperture assumption is not suitable for the radio telescope with large aperture.In this paper,a gradient segments superposition method for calculating the wind load has been proposed.The proposed method has been constructed by combining two regional divisions.First,reflecting surface has been evenly divided in the altitudinal direction.Second,the reflecting surface has been divided into several uniform rings assuming that the wind load coefficient on different rings are different.For the 110 m aperture radio telescope,the wind load estimation results differ by 28%.After that,a structural dynamics model of telescope has been established and a fuzzy PID controller has been designed to reduce wind disturbance.The Root Mean Square Error of telescope pointing under wind disturbance has been reduced by 67.8%.It is suggested that the proposed wind load estimation method has lay a solid foundation for the design of the large telescope system under wind disturbance.
