Deployable high-frequency mesh reflector antennas for future communications and obser- vations are required to obtain high gain and high directivity. In order to support these new missions, reflectors with high surfac...Deployable high-frequency mesh reflector antennas for future communications and obser- vations are required to obtain high gain and high directivity. In order to support these new missions, reflectors with high surface accuracy are widely required. The form-finding analysis of deployable mesh reflector antennas becomes more vital which aims to determine the initial surface profile formed by the equilibrium prestress distribution in cables to satisfy the surface accuracy requirement. In this paper, two form-finding methods for mesh reflector antennas, both of which include two steps, are pro- posed. The first step is to investigate the prestress design only for the cable net structure as the circum- ferential nodes connected to the supporting truss are assumed fixed. The second step is to optimize the prestress distribution of the boundary cables connected directly to the supporting truss considering the elastic deformation of the antenna structure. Some numerical examples are carried out and the simulation results demonstrate the proposed form-finding methods can warrant the deformed antenna reflector surface matches the one by design and the cable tension forces fall in a specified range.展开更多
Passive intermodulation（PIM） has gradually become a serious electromagnetic interference due to the development of high-power and high-sensitivity RF/microwave communication systems, especially large deployable mesh...Passive intermodulation（PIM） has gradually become a serious electromagnetic interference due to the development of high-power and high-sensitivity RF/microwave communication systems, especially large deployable mesh reflector antennas. This paper proposes a field-circuit coupling method to analyze the PIM level of mesh reflectors. With the existence of many metal–metal（MM） contacts in mesh reflectors, the contact nonlinearity becomes the main reason for PIM generation. To analyze these potential PIM sources, an equivalent circuit model including nonlinear components is constructed to model a single MM contact so that the transient current through the MM contact point induced by incident electromagnetic waves can be calculated. Taking the electric current as a new electromagnetic wave source, the far-field scattering can be obtained by the use of electromagnetic numerical methods or the communication link method. Finally, a comparison between simulation and experimental results is illustrated to verify the validity of the proposed method.展开更多
A well-designed reflector surface with high beam pointing accuracy in electromagnetic performance is of practical significance to the space application of cable mesh reflector antennas. As for space requirements, cir-...A well-designed reflector surface with high beam pointing accuracy in electromagnetic performance is of practical significance to the space application of cable mesh reflector antennas. As for space requirements, cir- cular polarizations are widely used in spaceborne antennas, which usually lead to a beam shift for offset reflectors and influence the beam pointing accuracy. A two-step structural design procedure is proposed to overcome the beam squint phenomenon for high beam pointing accuracy design of circularly polarized offset cable mesh reflectors. A simple structural optimal design and an integrated structural electromagnetic optimization are combined to alleviate the beam squint effect of circular polarizations. It is imple- mented by cable pretension design and adjustment to shape the offset cable mesh surface. Besides, in order to increase the efficiency of integrated optimization, an update Broy- den-Fletcher-Goldfarb-Shanno （BFGS） Hessian matrix is employed in the optimization iteration with sequential quadratic programming. A circularly polarized offset cable mesh reflector is utilized to show the feasibility and effectiveness of the proposed procedure. A high beam pointing accuracy in order of 0.0001~ of electromagnetic performance is achieved.展开更多
Owing to manufacturing errors,the surface accuracy of a mesh reflector antenna decreases after fabrication compared with the design results;thus,it is necessary to adjust the surface before launching.The adjustment is...Owing to manufacturing errors,the surface accuracy of a mesh reflector antenna decreases after fabrication compared with the design results;thus,it is necessary to adjust the surface before launching.The adjustment is faced with 3 problems:First,the prototype physical model is unknown;i.e.,the physical model with manufacturing errors is different from the mathematical model.Second,the adjustment target is difficult to determine;i.e.,the antenna is adjusted on ground but works in space;there is a problem of an inconsistent adjustment target due to the different environments.Third,the efficiency is low;i.e.,the larger the aperture is,the more complex the structure is and the longer the adjustment time is;the efficiency restricts the antenna development cycle.To address these problems,a surface adjustment method considering the space–ground consistency of the adjustment target is proposed in this study.First,the characteristics of the cable-net structure were analyzed,and a method to modify the mathematical model by measuring part of the cable force of the physical model is proposed,which reduces the difference between 2 models.Second,based on the sensitivity matrix,an adjustment method for selecting key cables is proposed.Third,the influence of gravity and temperature on the surface was analyzed,and a preadjustment method considering the space–ground consistency of the adjustment target is proposed.Finally,simulation and prototype experiments were conducted to verify the accuracy and efficiency of the proposed methods,which can effectively support the ground preadjustment of a large-aperture mesh reflector antenna and improve the surface accuracy on orbit.展开更多
基金supported by National Natural Science Foundation of China (Grant No.51375360)
文摘Deployable high-frequency mesh reflector antennas for future communications and obser- vations are required to obtain high gain and high directivity. In order to support these new missions, reflectors with high surface accuracy are widely required. The form-finding analysis of deployable mesh reflector antennas becomes more vital which aims to determine the initial surface profile formed by the equilibrium prestress distribution in cables to satisfy the surface accuracy requirement. In this paper, two form-finding methods for mesh reflector antennas, both of which include two steps, are pro- posed. The first step is to investigate the prestress design only for the cable net structure as the circum- ferential nodes connected to the supporting truss are assumed fixed. The second step is to optimize the prestress distribution of the boundary cables connected directly to the supporting truss considering the elastic deformation of the antenna structure. Some numerical examples are carried out and the simulation results demonstrate the proposed form-finding methods can warrant the deformed antenna reflector surface matches the one by design and the cable tension forces fall in a specified range.
文摘Passive intermodulation（PIM） has gradually become a serious electromagnetic interference due to the development of high-power and high-sensitivity RF/microwave communication systems, especially large deployable mesh reflector antennas. This paper proposes a field-circuit coupling method to analyze the PIM level of mesh reflectors. With the existence of many metal–metal（MM） contacts in mesh reflectors, the contact nonlinearity becomes the main reason for PIM generation. To analyze these potential PIM sources, an equivalent circuit model including nonlinear components is constructed to model a single MM contact so that the transient current through the MM contact point induced by incident electromagnetic waves can be calculated. Taking the electric current as a new electromagnetic wave source, the far-field scattering can be obtained by the use of electromagnetic numerical methods or the communication link method. Finally, a comparison between simulation and experimental results is illustrated to verify the validity of the proposed method.
文摘A well-designed reflector surface with high beam pointing accuracy in electromagnetic performance is of practical significance to the space application of cable mesh reflector antennas. As for space requirements, cir- cular polarizations are widely used in spaceborne antennas, which usually lead to a beam shift for offset reflectors and influence the beam pointing accuracy. A two-step structural design procedure is proposed to overcome the beam squint phenomenon for high beam pointing accuracy design of circularly polarized offset cable mesh reflectors. A simple structural optimal design and an integrated structural electromagnetic optimization are combined to alleviate the beam squint effect of circular polarizations. It is imple- mented by cable pretension design and adjustment to shape the offset cable mesh surface. Besides, in order to increase the efficiency of integrated optimization, an update Broy- den-Fletcher-Goldfarb-Shanno （BFGS） Hessian matrix is employed in the optimization iteration with sequential quadratic programming. A circularly polarized offset cable mesh reflector is utilized to show the feasibility and effectiveness of the proposed procedure. A high beam pointing accuracy in order of 0.0001~ of electromagnetic performance is achieved.
基金supported by the National Natural Science Foundation of China(Nos.U2241247 and 52475281)the Civil Aerospace Technology Research Project(D030206)+2 种基金the Open Project of Yunnan Precious Metals Laboratory Co.,Ltd(YPML-2023050244)the academician expert workstation of Yunnan(No.202305AF150170)the Fundamental Research Funds for the Central Universities(No.QTZX24002).
文摘Owing to manufacturing errors,the surface accuracy of a mesh reflector antenna decreases after fabrication compared with the design results;thus,it is necessary to adjust the surface before launching.The adjustment is faced with 3 problems:First,the prototype physical model is unknown;i.e.,the physical model with manufacturing errors is different from the mathematical model.Second,the adjustment target is difficult to determine;i.e.,the antenna is adjusted on ground but works in space;there is a problem of an inconsistent adjustment target due to the different environments.Third,the efficiency is low;i.e.,the larger the aperture is,the more complex the structure is and the longer the adjustment time is;the efficiency restricts the antenna development cycle.To address these problems,a surface adjustment method considering the space–ground consistency of the adjustment target is proposed in this study.First,the characteristics of the cable-net structure were analyzed,and a method to modify the mathematical model by measuring part of the cable force of the physical model is proposed,which reduces the difference between 2 models.Second,based on the sensitivity matrix,an adjustment method for selecting key cables is proposed.Third,the influence of gravity and temperature on the surface was analyzed,and a preadjustment method considering the space–ground consistency of the adjustment target is proposed.Finally,simulation and prototype experiments were conducted to verify the accuracy and efficiency of the proposed methods,which can effectively support the ground preadjustment of a large-aperture mesh reflector antenna and improve the surface accuracy on orbit.
