Mesh Reflector Research Articles

Numerical Investigation on the Thermal Characteristics of Lightweight Metal Mesh-Based Reflector Antenna with Various Knitting Conditions

Proper prediction of the temperature variation in a metallic wire mesh for spaceborne large deployable reflector antennas is essential for evaluating the dimensional stability of the antenna under extreme on-orbit thermal environments. However, predicting the temperature of a mesh is difficult because of its complex yarn configuration. To analyze the thermal behavior of the spaceborne mesh antenna reflector, the thermal optical characteristics with various knitting methods of the metallic mesh were obtained experimentally in this study. Subsequently, to analyze the thermal sensitivity of the reflector based on its optical properties, an on-orbit thermal analysis of the mesh reflector was performed based on measurements of the mesh specimen. We also investigated the influence of deployable solar panels on the thermal gradient of the reflector.

Development of Lightweight 6 m Deployable Mesh Reflector Antenna Mechanisms Based on a Superelastic Shape Memory Alloy

This paper describes the design and experimental verification of a 6 m parabolic deployable mesh reflector antenna mechanism based on a superelastic shape memory alloy. This antenna mainly consists of a deployable primary reflector with a superelastic shape memory alloy-based hinge mechanism and a fixed-type secondary reflector mast, where a rotary-type holding and release mechanism and deployment speed control system are installed. The main feature of this antenna is the application of a superelastic shape memory alloy to the mechanism, which has the advantages of plastic deformation resistance, high damping, and fatigue resistance. A shape memory alloy is applied to the hinge mechanism of each primary reflector rib and to the rotary-type holding and release mechanism as a deployment mechanism. In addition, a superelastic shape memory alloy wire is applied to the antenna in the circumferential direction to maintain the curvature of the primary reflector. The effectiveness of the proposed mechanism design was verified through repeated deployment tests on models of the superelastic shape memory alloy-based hinge mechanism and the antenna system.

Design of deployable mesh reflector antenna based on cable-dome tensegrity structure

In large-aperture deployable antennas, such as the AstroMesh antenna, the back-to-back arrangement of double-layer paraboloids can lead to size and weight exceeding the limits of the launch vehicle. To address this, a deployable mesh reflector antenna based on a cable-dome tensegrity structure, composed of tension cables and compression rods, is proposed. The structure and elementary unit of the cable-dome are presented, followed by the introduction of a W-deployable truss to meet the single-layer boundary node-hanging requirements. The geometric parameters and deployment kinematics are analyzed, leading to the optimization and simulation of a 50 m-aperture antenna. Compared to a same-aperture AstroMesh antenna, the cable-dome antenna offers a smaller folded size and weight. Finally, a 2 m-aperture prototype was constructed, and its feasibility verified through deployment experiments and surface accuracy photogrammetry. The proposed cable-dome antenna shows significant potential in large-aperture deployable antenna applications.

Preliminary Design of a Lightweight Composite Backing Structure for a Satellite Antenna

AbstractThe paper consists of a preliminary design and analysis of a lightweight composite backing structure for a side deployable solid mesh reflector intended for telecom application in the Ka‐Band. As the entire antenna reflector must withstand the forces related to the launching loads, the focus is addressed to the stiffness of the composite backing structure, so that the reflective metallic mesh will not be affected during launching phase, thus with no influence over the possible deformation of the mesh and on its radio frequency performance. It is shown that the proposed concept withstands the imposed launching requirements with a compromise on mass properties.

Deployment Dynamic Modeling and Driving Schemes for a Ring-Truss Deployable Antenna

Mesh reflector antennas are widely used in space tasks owing to their light weight, high surface accuracy, and large folding ratio. They are stowed during launch and then fully deployed in orbit to form a mesh reflector that transmits signals. Smooth deployment is essential for duty services; therefore, accurate and efficient dynamic modeling and analysis of the deployment process are essential. One major challenge is depicting time-varying resistance of the cable network and capturing the cable-truss coupling behavior during the deployment process. This paper proposes a general dynamic analysis methodology for cable-truss coupling. Considering the topological diversity and geometric nonlinearity, the cable network’s equilibrium equation is derived, and an explicit expression of the time-varying tension of the boundary cables, which provides the main resistance in truss deployment, is obtained. The deployment dynamic model is established, which considers the coupling effect between the soft cables and deployable truss. The effects of the antenna’s driving modes and parameters on the dynamic deployment performance were investigated. A scaled prototype was manufactured, and the deployment experiment was conducted to verify the accuracy of the proposed modeling method. The proposed methodology is suitable for general cable antennas with arbitrary topologies and parameters, providing theoretical guidance for the dynamic performance evaluation of antenna driving schemes.

Scaling Laws for Deployable Mesh Reflector Antennas

This paper begins with the formulation of a general, rapid design method for deployable mesh reflector antennas based on the AstroMesh architecture. This method is then used to obtain estimates of the total mass, stowed envelope size, and fundamental natural frequency of vibration for antennas with a range of aperture diameters and focal lengths, assuming an operational radio frequency of 10 GHz. A study of the scaling trends of this reflector design shows that the distribution of prestress in the inner tension structure has a major impact on the mass of the outer perimeter truss. Based on this result, a prestress optimization problem to design reflectors of minimum mass is formulated, and analytical scaling laws are obtained for the mass, stowed envelope, and natural frequency of optimally prestressed reflectors with aperture diameters up to 200 m. It is then shown that aperture diameters of 70–100 m are at the limit of launchers that are currently available or under development. A semianalytical homogenization model that accurately estimates the fundamental natural frequencies for batten-supported and free-free boundary conditions is also presented.

Novel constant-height deployable mechanisms with only revolute joints and constructed deployable ring trusses for satellite mesh reflector antennas

Deployable mechanisms play an increasingly crucial role in aerospace, yet their design still faces challenges: 1) The folded height increases while its deployed height decreases, which is not conducive to improving the folding performance; 2) Compared with revolute joints, prismatic joints have relatively weak reliability in complex space environments. To address the above challenges, novel constant-height deployable mechanisms with only revolute joints are proposed in this paper. The deployable mechanisms exhibit one degree of freedom, enabling them to attain modular expansion. Subsequently, the mobility properties of these deployable mechanisms are substantiated through screw theory. Assembly strategies for constant-height deployable mechanisms are proposed, and deployable ring trusses are further constructed to provide support structures for satellite mesh reflector antennas. The kinematics are analyzed to investigate the deployable characteristics of the proposed deployable mechanisms and ring trusses. The prototypes of a deployable mechanism and a ring truss are established to validate the designed deployable mechanisms. This work contributes novel types of deployable mechanisms with potential advantages, aiming to function as valuable references for the design and analysis of deployable trusses.

Anti-creep pretension determination of a mesh reflector antenna for long term surface accuracy retention

During the in-orbit service, mesh reflector antennas inevitably withstand the long-term creep behavior, resulting in changes in material properties and loss of cable tensions, thus decreasing the structural stiffness and surface accuracy. Pretension design plays an important role for mesh reflector antennas in achieving high surface accuracy, and different levels of pretension also affect the antenna’s creep behavior in the time dimension, which can be actively utilized to improve stability of the antenna surface accuracy. In this paper, we present an anti-creep pretension determination method for mesh reflector antennas to improve the surface accuracy stability. The creep model in the discretized time domain is adopted to describe the cable creep behavior. The time-related nonlinear equilibrium equation of the mesh reflector antenna is established with the force density method. The time-related tangent stiffness matrix is derived and adopted to solve the nonlinear equilibrium equation by the Newton-Raphson method, providing an effective way to analyze the antenna creep phenomenon in the discretized time domain. Aiming to minimize the long-term peak value of the time-variant surface error, the pretension schemes are generated and optimized. Finally, this approach is effectively applied to a thirty-unit mesh reflector antenna and its feasibility and effectiveness are verified.

Research and Application on High Precision Measurement Method of Large Mesh Antenna Surface

Abstract The development process of large mesh antennas requires a significant investment of time and resources for iterative measurements and adjustments to achieve high precision in the large mesh reflector. In this paper, a novel measurement method for the precision of large mesh antenna surfaces is proposed to reduce the development process. Multiple measurement cameras have been utilized to set up a network system, enabling data integration for comprehensive analysis and computational calculations. In this approach, the implementation of a one-click and the rapid measurement function represent substantial advancements. The single measurement time has been successfully reduced from 40 minutes to 2 minutes, which addresses the challenge of high efficiency and precision measurement application on the complex mesh antenna surface. Then the optimization of calibration is accomplished through the meticulous measurement of network patterns, marker points, and reference bars to improve the precision accuracy on the foundation of rapid measurements, combined with the simulation analysis. The final results have been practically verified and successfully applied to model development, which provides a crucial reference for subsequent endeavors involving the rapid and automated measurement of similar antennas.

Surface accuracy prediction method for mesh reflector antenna considering uncertainty factors in manufacturing process

The cable-net structure of mesh reflector antenna meets the requirement of surface accuracy by optimizing the shape and tension. However, in the process of manufacturing and assembly, there are inevitable random errors and structure gravity, which lead to the displacement of the nodes in surface, the surface accuracy of the antenna decreases after fabrication eventually. It is challenging to analyze the uncertainty factors and the effects on the surface accuracy. Therefore, this paper analyzes the uncertainty factors of the antenna during fabrication and proposes a method to predict the surface accuracy of the antenna after manufacturing and assembly. Firstly, based on the equilibrium equation of the cable-net structure, the mechanism of node displacement induced by uncertainty factors leading to the reduction of surface accuracy is analyzed. Secondly, based on the structure characteristics and manufacturing conditions of the antenna, the uncertainty factors including cable-net manufacturing and assembly errors, cable-truss assembly errors and gravity are analyzed qualitatively and quantitatively, the distributions of the uncertainty factors are given. Thirdly, based on Monte Carlo method, the mean and interval of the surface accuracy of different dimension parameters are predicted, the empirical prediction formulas of the surface accuracy mean and interval are fitted. Finally, the accuracy and effectiveness of the proposed formulas are verified by several numerical simulations and surface accuracy measurement experiments. The prediction method can effectively guide the design and craft of large-aperture mesh reflector antenna.

Design of a Deployable Broadband Mesh Reflector Antenna for a SIGINT Satellite System Considering Surface Shape Deformation.

In this paper, we propose a deployable broadband mesh reflector antenna for use in signals intelligence (SIGINT) satellite systems, considering performance degradation due to shape deformation. To maximize gain by increasing the diameter of the reflector while reducing the weight of the antenna, the reflector of the antenna is designed using lightweight silver-coated Teflon mesh. The mesh reflectors are typically expanded by tension to maintain their parabolic structure; thus, shape deformation cannot be avoided. This shape deformation results in shape differences between the surface of the mesh reflector and the ideal parabolic reflector, thus resulting in the degradation of the performance of the mesh reflector antenna. To observe this degradation, we analyze antenna performance according to the number of arms, the number of joints, the feed distance, and the distance from the reflector center to each joint. The performance of the mesh reflector antenna is examined using an effective lossy conducting surface (ELCS) that has the same reflectivity as the silver-coated Teflon mesh to reduce simulation time and computing resources. The designed silver-coated Teflon mesh reflector and the double-ridged feed antenna are fabricated, and the bore-sight gain is measured using the three-antenna method. The measured bore-sight gain of the proposed antenna is 31.6 dBi at 10 GHz, and the measured and simulated results show an average difference of 3.28 dB from 2 GHz to 18 GHz. The proposed deployable mesh reflector antenna can be used in a variety of applications where small stowed volume is required for mobility, such as mobile high-gain antennas as well as satellite antenna systems. Through this study, we demonstrate that shape deformation of the mesh reflector surface significantly affects the performance of reflector antennas.

Optimized Surface Adjustment Method for Large Deployable Cable Network Antennas

Large deployable mesh reflectors typically require high surface accuracy and have large apertures. The accumulation of machining errors in a large number of cables can lead to significant deviations between the final manufactured surface and the theoretical surface, particularly due to the large number of cables involved. Adjusting the mesh reflector is often necessary to meet the surface accuracy requirements. However, traditional surface adjustment methods can be challenging to converge and time-consuming. To address this issue, our paper proposes an engineering surface based on measured manufacturing errors as a substitute for the theoretical surface. This method can save time on the coarse adjustment of surface accuracy for large deployable mesh reflectors, reducing the overall surface accuracy adjustment time by 30%.

Optimal self-stress determination for high-accuracy mesh reflectors design considering the pillow distortion

The pillow distortion is a significant barrier to the high-accuracy design of mesh reflector antennas, which is caused by the compatible deformation between the flexible cable network and the metallic mesh, manifested as the pillow-like distortion of the mesh reflecting surface. The pillow effect deviates the mesh surface from the desired paraboloidal shape leading to the surface error. Unfortunately, current researches usually neglect this effect in the mesh reflector design due to its complicated formulation. Focusing on this phenomenon, this paper proposed an optimal self-stress determination method for high-accuracy mesh reflector design. Firstly, a mechanism model of pillow distortion is proposed based on the cable-membrane constitutive models and coupling relations. The integrated equilibrium equation of the mesh reflector is established and solved by the dynamic relaxation (DR) method, which effectively analyses the influence of the pillow distortion on the mesh reflector. Then, considering the pillow distortion, a high-accuracy design method for the mesh reflector is proposed by optimising the geometrical sizes of the cable network and the metallic mesh combining the DR method with optimisation algorithm. Finally, the proposed method is effectively applied to the design of an eighteen-unit mesh reflector antenna, and the feasibility and effectiveness of the proposed method are demonstrated.

A novel identification approach of mesh reflector based on tie cable tension sensing

The mesh reflector suffers inevitably from complicated environmental interferences during long-term on-orbit operation and consequently the reflector may deviate significantly from its initial state. It is thus crucial to identify the deformed reflector on-orbit in order to evaluate timely the mesh reflector accuracy. However, the existing reflector identification methods are difficult to achieve this object as the most of them need to install additional equipment on antenna or satellite. Aiming at realizing on-orbit mesh reflector identification, a novel identification approach based on tie cable tensions sensing (TCTS) is proposed in the paper. The TCTS method leverages real-time measurements of tie cable tensions through embedded force sensors to calculate the remaining cable tensions required to address reflector deformations. For this purpose, an optimization problem is established based on tension balance equation and then solved using a proposed iteration solution algorithm incorporating the genetic algorithm. The actual configuration of mesh reflector is then determined by all cable tensions according to the force density method and the reflector can be identified ultimately. The simulated studies on reflector identification of a mesh reflector with 8 m aperture diameter are conducted under temperature loads and cable stiffness degradations respectively. The results indicate that the TCTS method possesses high reflector identification accuracy and good anti-noise capability under different environmental interferences. Furthermore, a reflector identification method based on partial tie cable tensions sensing (PTCTS) is developed in order to reducing system complexity and cost. The sensitivity analyses of tie cable tensions are performed in order to provide a reference for location placement of force sensors in the PTCTS method. The simulated results indicate that the optimized location placement scheme can enhance significantly the reflector identification accuracy of PTCTS method. Besides, the PTCTS method exhibits equal anti-noise capability with the TCTS method. Finally, the experimental studies are conducted on reflector identification of a mesh reflector test model with 1.5 m diameter and 0.5 m height under cable stiffness degradations. Through comparing with the reflector identification results obtained by the photogrammetry method under different cable stiffness degradation degrees, the accuracy and effectiveness of the TCTS/PTCTS methods are demonstrated experimentally.

A 7 m × 1.5 m Aperture Parabolic Cylinder Deployable Mesh Reflector Antenna for Next-Generation Satellite Synthetic Aperture Radar

A high priority next-generation satellite remote sensing mission necessitates a lightweight deployable antenna that can fit in the package of low-Earth orbit small satellites. In this work, we present the development of a 7 m×1.5 m aperture C-Band parabolic cylinder mesh reflector along with a 1×32 element linear patch array feed. The detailed and tailored mechanical design, full-wave analysis, and measurements of the reflector are elaborated. The reflector is constructed with a mesh surface with unique deployment mechanisms for weight reduction and stowage. The linear microstrip patch array feed is designed with a lightweight honeycomb substrate and is used for the breadboard testing of the parabolic cylinder reflector. The antenna achieved the desired surface accuracy and a measured gain of 42.06 dBi at 5.357 GHz, with half-power beamwidths of 0.52° and 2.35° in the two principal planes.

An Electromechanical Matching Design Method for Faceted Surface of Mesh Reflector

The faceted surface is used in mesh reflectors to reflect electromagnetic (EM) signals. The matching design method of surface geometry is developed by considering EM performance. The geometrical model of faceted surface is established to avoid the facets overlap by using the force density method, and the far-field scattered by mesh reflector is derived to reveal the relationship between the faceted surface and EM performance. To improve the computational efficiency, the double integral of the far-field is derived in a closed-form expression, and a refinement procedure of EM grids for facets is proposed to homogenize the grids. The electromechanical coupling optimization model is established, and the comparative analysis is carried out, respectively. Numerical results show that the proposed method can obtain the higher gain with a larger surface error of the mesh reflector by adjusting the distribution of the surface faceted error.

Pretension design for mesh reflector antennas with flexible trusses and hinges based on the equilibrium matrix method

In the current pretension design of mesh reflector antennas based on the equilibrium matrix method (EMM), the truss and hinge deformation cannot be accurately captured, which will deteriorate the shape accuracy of the antenna. To solve this problem, this paper proposes a new EMM-based pretension design method. In this method, the rod of the truss is modeled as Euler-Bernoulli beam, and the joint of the hinge is treated as the spring with six degrees of freedom. Based on the beams and springs, the systematic equilibrium equation of the mesh reflector antenna is established considering the flexibility of rods and hinges. Then, the mesh reflector antenna is divided into the inner cable network and boundary cable-truss-hinge assembly. The equilibrium equation of the boundary cable-truss-hinge assembly is solved by the force density method to calculate the truss and hinge deformation. The equilibrium equation of the inner cable network is solved by the EMM to fix all free nodes at desired positions. Combined with the active-set optimization algorithm, the required cable tensions are obtained by taking the mean tension ratio of the cable network as the objective function, thus ensuring high shape accuracy. Lastly, the proposed method is applied to the mesh reflector antenna and verified by ABAQUS.

Thermal design optimization method of mesh reflector antennas considering the interaction between cable net and flexible truss

Thermal design optimization method of mesh reflector antennas considering the interaction between cable net and flexible truss

Form-finding design optimization method of cable mesh reflectors based on a weighting surface accuracy with electromagnetic performance

Form-finding design optimization method of cable mesh reflectors based on a weighting surface accuracy with electromagnetic performance

An Antenna Pattern Correction Algorithm for Conical Scanning Spaceborne Radiometers: The CIMR Case

The rapid evolution of the effects observed in various areas of our planet related to climate change poses urgent questions about the knowledge of the state of the polar area and requires satellite acquisitions with fine spatial resolution and high accuracy to develop advanced products. The Copernicus Imaging Microwave Radiometer (CIMR) mission, based on a multifrequency microwave radiometer and designed to observe the ocean, sea ice, and Arctic environment, requires brightness temperature measurements with a total absolute uncertainty of 0.5 K and a spatial resolution of 5 km. This constraint demands very large reflectors with a gain value of tens of decibels. Mechanical constraints will be attained by using a mesh reflector, which guarantees the required resolution but with the drawback of a radiation pattern characterized by many grating lobes that contaminate the value of the brightness temperature associated with the boresight position. In this article, an antenna pattern correction (APC) is proposed to correct these effects. The algorithm takes advantage of an iterative formulation based on the Jacobi Method, providing a suitable correction that depends on the chosen spatial resolution. The APC algorithm was tested at both K- and Ka-bands with similar performance. Here, only the results from the latter are shown, as its antenna pattern is the most challenging among CIMR.