Space Antenna Reflectors Research Articles

Development method of splitting the radio-reflective large-sized reflector surface into cutting patterns made of mesh with coarse cells

An important design component of space antenna reflectors is a reflecting surface. At present, metallic knitted mesh fabric is most often used as a reflective surface; it fully meets the requirements for such surfaces in terms of physical and mechanical properties. Particularly important characteristics for large-sized reflectors are low specific gravity and high light transmission coefficient, which a mesh with coarse cells provides. However, the structural features of this mesh fabric impose additional requirements on its use as a reflective surface for large-sized transformable reflectors. The article deals with a special approach to designing patterns for a reflective surface made of mesh with coarse cells. The developed pattern cutting option allows to obtain a reflective surface with the least distortion (error), in accordance formulated criteria. The authors have suggested the option of obtaining cutting patterns of metallic mesh fabric, described the advantages of the proposed option over the classical one. The cutting pattern of the parabolic surface for the offset reflector was obtained. The proposed cutting pattern option was analyzed. Furthermore, optimization was carried out, which made it possible to maintain the integrity of the cellular structure of patterns along one loop row. The compared results show that the developed cutting pattern option completely complies with the requirements and it can be used to form a reflective surface from the metallic knitted mesh with coarse cells.

Form-finding and shape adjustment of cable-membrane reflectors

Cable-membrane reflector is a highly nonlinear flexible structure, which can represent a specific surface shape under the proper combination of cable tension and membrane stress. AstroMesh reflector is a representative of cable membrane reflector, which has advantages of large aperture, easy folding, and light weight, and is increasingly utilized in space antenna reflectors. In this paper, a finite element model of the cable-membrane structure is established together with the corresponding incremental equilibrium equation which provides the sensitivity of the nodal position with respect to the geometric parameter of the cables and triangular membranes. A form-finding strategy is detailed, which aims at a configuration with the reflector nodes locating on a specified paraboloid while all cables and membranes are tensioned uniformly as possible. In addition, the surface precision of the reflector is reduced due to the inevitable errors in the manufacturing process. Therefore, the tension ties in the cable network is designed to be adjustable to solve this problem. Carefully changing the length of these cables can increase the reflector surface precision, which is referred as shape adjustment. An adjustment strategy with model updating is proposed. The model updating using the measured positions of the reflector nodes can dramatically reduce the discrepancy of the finite element model with respect to the actual reflector, thus remarkably improving the efficiency of shape adjustment. Numerical example and physical experiment demonstrate the effectiveness of the proposed method.

Correlation between Preload and Geometric Characterisation of metal meshes for space antenna reflectors

The paper deals with digital image processing techniques to analyse the shape of the main voids in the metallic mesh of large deployable antennas. The shape of the holes in the mesh influences the electromagnetic performances as the working frequencies and the polarisation effects. The analysis compares two types of mesh subjected to a series of equal loads in two directions; for this task, a dedicated testing machine is used. The paper presents an approach to defining an effective and averaged repetitive pattern. Thus, a statistical point of view of the entire mesh is given, applicable to studying the behaviour of a full reflector, to avoid being affected by local texture defects.

An approach to design of large-sized deployable hoop space antenna reflector

Amongst the large-sized transformable space antennas, the most attention is currently paid to developing of antennas with hoop-shaped reflectors. The developers are faced with the necessity of looking for optimal design concepts. This paper shows the various concepts of building of the reflectors of the cable-rod scheme, containing a circular load-bearing framework (load-bearing rim) with a deployment drive set on it and the reflecting surface shape-generating structure, assembled into a single construction by the cable and rod elements. The difference between the proposed design concepts of the reflectors is the various structures of the controllable unfolding mechanisms. In the first alternative of the reflector structure, the unfolding process is supported by the cable, which restrains relative displacements of the tips of the initially compressed springs. The second alternative supposes the cable not to be the restraining element, but an active unit of the unfolding mechanism. This paper also describes various alternatives for connection between tension tie cables and the load-bearing rim. It is shown that the alternative of connection of the tension tie cables to the middles of the load-bearing rim edges allows to perform stress analysis of the structure elements and to obtain required characteristics of the spring drive. The numerical calculations for optimal angular position of the deployment drive pulleys holder relative to the sections of the load-bearing rim for the second alternative of the reflector design, which provides the most force effect on shape-generating structure of the reflector, when the knitted mesh fabric is being pulled, are under consideration in this article. The calculations are confirmed by experimental investigations.

Investigation on design methods for cable mesh configuration of deployable space antenna reflector

Mesh reflectors are always a preferable option for large size deployable antenna reflector over solid surface reflectors due to their flexibility of adjustment in minimum possible space and ability to get deployed to full configuration in space. Maintaining surface properties and accuracy are two important requirements in the design of the mesh reflector for the performance of cable network antenna reflectors. The present work considers the various design approaches for cable mesh configuration of space deployable antenna reflectors. The equal force density shape forming criteria such is applied for obtaining the desired parabolic curvature of the mesh configuration. The ring structure for the deployable mechanism is considered as rigid linkages for designing mesh configuration. A generalized numbering scheme for nodes and cable mesh link is formulated for carrying forward various shapes forming criteria which help in making an algorithm. The algorithm for a better understanding of these methods is developed using MATLAB with nodal coordinates and its connection. Mesh configuration is developed with a different number of divisions. A study is also carried out for finding the required number of divisions for a highly accurate parabolic profile for a particular band frequency. A demonstration model is developed and a comparison of the coordinates of the prototype is made with those arrived at using the model.

Экспериментальное определение механических и теплофизических характеристик углепластика тонкостенной оболочки антенного рефлектора

High requirements are imposed on the mass and dimensional stability of reflectors of onboard mirror space antennas in promising communication satellites. To meet these requirements, new design and layout schemes for reflectors using composite materials are being developed. The use of flat reinforced carbon fabric composites in these designs is of particular interest. A technique is developed for the experimental determination of mechanical and thermophysical characteristics of the carbon fiber used in a thin-walled shell (0.6 mm) of the onboard space antenna reflector. Data are obtained on the elastic modulus of the carbon fiber based on Aspro-A80 carbon fabric and Huntsman Araldite LY8615 US/XB 5173 Hardener epoxy compound in two directions. The thermal conductivity of the material in the plane of reinforcement is determined.

Research of temperature and stress-strain state of mirror space antenna reflector with fins based on nonbraided polyester material

A number of designs of reflectors of a mirror space antenna in the form of a thin-walled shell made of high-modulus carbon fiber reinforced with a developed finning system in the form of three-layer panels with a filler made of nonwoven polyester material is considered. Within the framework of the finite element modeling, a comparative analysis of serviceability under operating conditions (radiative heat transfer in open space conditions) has been carried out. Patterns of temperature distribution and thermal displacements along the reflector surface have been obtained. According to the results of the research, MSA reflector’s design layout with the best indicators has been chosen.

Active Adjustment of Surface Accuracy for a Large Cable-Net Structure by Shape Memory Alloy.

The high surface accuracy design of a cable-net antenna structure under the disturbance of the extremely harsh space environment requires the antenna to have good in-orbit adjustment ability for surface accuracy. A shape memory cable-net (SMC) structure is proposed in this paper and believed to be able to improve the in-orbit surface accuracy of the cable-net antenna. Firstly, the incremental stiffness equation of a one-dimensional bar element of the shape memory alloy (SMA) to express the relationship between the force, temperature and deformation was effectively constructed. Secondly, the finite element model of the SMC antenna structure incorporated the incremental stiffness equation of a SMA was established. Thirdly, a shape active adjustment procedure of surface accuracy based on the optimization method was presented. Finally, a numerical example of the shape memory cable net structure applied to the parabolic reflectors of space antennas was analyzed.

Experimental studies on the mechanical properties of a woven composite material for space antenna reflector

In this paper the results of mechanical tests of a biaxial woven composite are presented. This material was used for a new design of deployable precision space antenna reflector of large aperture. The experiments included standard tensile tests at low, normal and high temperatures, compression and shear tests. An additional nonstandard bending test was performed to determine the smallest radius of curvature that a specimen could withstand without fracture. The experiments showed the perspectives for the use of the studied composite in the reflector structure. The determined mechanical properties can be used for numerical modeling of the reflector behavior.

Перспективы повышения размерной стабильности и весовой эффективности рефлекторов зеркальных космических антенн из композиционных материалов

Перспективы повышения размерной стабильности и весовой эффективности рефлекторов зеркальных космических антенн из композиционных материалов

Self-Sensing Electromagnetic Transducer for Vibration Control of Space Antenna Reflector

Space antenna reflectors are used by space vehicles to communicate with ground stations. These reflectors are generally subject to broadband random vibration and shock conditions during shipment and vehicle launch. While active vibration control methods can reduce any unexpected responses, sensors, controllers, power amplifiers, and actuators are all required to implement the control system. These additional external devices increase both the weight and the cost of the reflector, and reduce the reliability and safety of the space product. This study proposes a novel self-sensing vibration control method and applies a self-sensing electromagnetic transducer to suppress the vibration of a space antenna reflector. This transducer is used bifunctionally, acting as both an isolator and a velocity sensor. The vibration control principle of the proposed method is analyzed. A governing equation is established using the finite element method. A type of degree of freedom reduction method is used to obtain the response of the space antenna reflector. A ground experiment is then set up. The results demonstrate that the proposed self-sensing vibration control method can reduce the second-order and third-order vibrations of the space antenna reflector by 4 and 9 dB, respectively.

Elaboration of the technology of producing a space-antenna reflector

A method for producing a reflector for a mirror space antenna by vacuum infusion from thin and low-porosity carbon-fiber fabric is discussed. The results of studying the influence of the porosity of carbonfiber fabric on its shape-generating properties when placing it on the double-curvature surface of a molding tool are given. Three methods of placement are suggested. The kinetics of the soaking process is evaluated theoretically and experimentally.

Analytical modeling of the flexible rim of space antenna reflectors

This paper presents a geometrically nonlinear analytical model of the flexible cylindrical rim of a deployable precision large space antenna reflectors made of shape-memory polymer composites. A nonlinear boundary-value problem for the rim in the deformed (folded) configuration is formulated and exact analytical solutions in elliptic functions and integrals describing the deformation modes of the rim are obtained. Exact analytical solutions based on the geometrically nonlinear model are obtained and can be used to determine preliminary geometric dimensions and optimal shape of the flexible rim along with the estimation of the accumulated energy.

Comparison of space antennas mirror reflectors parameters made of composite materials

Communication satellites today are fitted with one or more parabolic antenna reflectors. The unique mechanical and thermal characteristics mean that space antenna reflectors (AR) are most frequently fabricated from carbon-fibre reinforced plastics (CFRP). The reflector design must meet the stringent requirements for low linear density and high dimensional stability.

ОПРЕДЕЛЕНИЕ КОНСТРУКТИВНОГО ОБЛИКА РЕФЛЕКТОРА ЗЕРКАЛЬНОЙ КОСМИЧЕСКОЙ АНТЕННЫ ИЗ КОМПОЗИЦИОННОГО МАТЕРИАЛА

This article describes search studies of optimal design and technological solutions for the ultralight mirror space antenna reflectors made of CFRP. The studies included finite element modeling of the reflector temperature and stress-strain state in the geostationary orbit. As a result of comparing the results of a number reflector variants modeling, a design was chosen, with minimal values of temperature displacements and linear density

Comparative analysis of the honeycomb and thin-shell space antenna reflectors

Parabolic three-layered reflectors from polymer composite materials with the aluminium honeycomb fillers became widely used in space communication systems in the past decades. There are technological possibilities for creating reflectors in the form of thin-walled ribbed shell with the lower linear density than that of the three-layered structures. The paper presents the results of the temperature and stress-strain analysis for the two types of structures, which could help to select the variant with the best performance characteristics.

An investigation into shape and vibration control of space antenna reflectors

A study into the shape and active vibration control of antenna reflectors, an important member of the space structures, is carried out in this paper. Geometric nonlinear analysis is considered for performance evaluation of antenna reflectors, as very high precision is an important aspect of space structures. An effort has been made to demonstrate the importance of functionally graded materials in space structures. Piezolaminated structures have been used for shape and vibration control applications for many years. However, due to the problems like debonding and delamination, the reliability of these materials in space structures is still uncertain. To overcome these problems, patches made of functionally graded piezoelectric material (FGPM) are used for shape and vibration control of antenna reflectors in this investigation. FGPM patches are also used to demonstrate the beam-shaping and beam-steering application of antenna reflectors. For the active vibration control application, a fuzzy-logic controller (FLC) is designed and validated with the experimental results. An experimental study has been conducted for comparing the performance of different controllers in the context of vibration reduction. The FLC is then used for active vibration control of an antenna reflector under the application of thermal impact and sinusoidal loading.

Optical characterisation of metallic meshes for space antennas transformable reflectors

The paper deals with metallic meshes for space antenna transformable reflectors. Optical characteristics of four metallic meshes (15 micron tungsten, 15 micron gold-plated tungsten, 20 micron molybdenum, and 50 micron Ni-coated steel) were investigated with the Nikolet IS50 spectrophotometer. The spectral optical characteristics of these metallic meshes in the range from 0.4 to 2.5 microns are required for thermal design of space antenna reflectors.

Kinematics of deployment of petal-type large space antenna reflectors with axisymmetric petal packaging

This paper is concerned with the kinematics of the deployment of petal-type large space antenna reflectors with axisymmetric petal packaging. The classification and technical design solutions for petal deployment mechanisms and the results of their comparative analysis have been presented.

Substantiation of the Structural-Layout Scheme of the Mirror-Space-Antenna Reflector with a High Shape Stability and a Low Density per Unit Length

Problems of designing space-antenna reflectors from composite materials for promising telecommunication satellites are considered. Selection of designs is based on the numerical modeling of heat-transfer and mechanics processes corresponding to orbital-flight conditions.