Cable Mesh Reflector Research Articles

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

Force density sensitivity form-finding design method for cable-mesh reflector antennas considering interactive effects between cable network and supporting truss

Form-finding design is critical in determining whether a cable-mesh reflector antenna can meet electrical performance requirements. However, the current methods rarely consider the interactive effects between the cable network and the supporting truss in the form-finding process, which requires more iteration steps for good design results. This study presents a force density sensitivity form-finding design method for cable-mesh reflector antennas based on systematic equilibrium equations. The sensitivity matrix of the support truss vertex and the cable network free node is derived with respect to force density, and the form-finding process of the reflector antenna is transformed into a sequential quadratic programming problem that can be easily solved. The antenna meets the accuracy requirements, and has a more uniform distribution of internal cable net tension and a smaller truss deformation as a result of constraining the vertex deformation of the supporting truss and cable tension. For practical engineering problems, more accurate design results can be obtained quickly. The effectiveness of the proposed method is verified through numerical examples.

Integrated structural-electromagnetic optimization of cable mesh reflectors considering pattern degradation for random structural errors

To alleviate the effects of random structural errors on the radiation performance and directly guide the structural design of cable mesh reflectors, an integrated structural-electromagnetic optimization procedure is proposed considering the radiation pattern degradation for random structural errors. Based on analytical expressions and the structural sensitivity concept, the radiation pattern is directly expressed as two matrix-form functions with respect to the random structural errors. By applying the pattern calculation into the multidisciplinary design and selecting the average boresight directivity as the objective function, an optimum result with better radiation performance compared with the traditional structural design is obtained. To reveal the fundamentals of the optimum result, the concept of sensitivity analysis of the average boresight directivity with respect to the random structural errors is introduced. The effectiveness and benefits of this study are demonstrated via an offset cable mesh reflector.

Conceptual design of a new thermal‐electric conversion device in lightweight concentrating solar thermal power system

AbstractConcentrating solar thermal power (CSTP) technology has become a hot issue in the present research because of its high conversion efficiency. However, traditional schemes cannot be widely applied due to their complex structure, low power density, and high cost. In view of this, based on a new type of lightweight cable mesh reflector structure and the Rankine cycle, a new conceptual design of thermal‐electric conversion device in CSTP system is proposed. The process of thermal‐electric conversion is actualized through smart and lightweight structural design; the performance estimation of the device is carried out through focusing performance analysis and thermodynamic analysis; the cycling feasibility is verified through multifield coupling simulation analysis. Compared with the existing thermal‐electric conversion devices, the device proposed in this paper has higher power‐to‐weight ratio. And the power generation system that combines the proposed device with the flexible cable net reflector has the characteristics of lightweight, portability, and small land area, which has a great significance for the popularization and application of distributed layout CSTP system.

A novel ultralight dish system based on a three-extensible-rod solar tracker

The use of dish systems is among the most potential methods for solar power collection. However, the popularization of the application of traditional dish systems has been impeded because they are heavy, structurally complex, and costly. Accordingly, a novel ultralight dish system is proposed; it consists of a cable mesh reflector, an ultralight thermoelectric conversion device, and a three-extensible-rod (TER) solar tracker. Compared with previous reflectors consisting of rigid solid panels, the reflector of the proposed dish system (PDS) adopts an ultralight rigid–flexible combined structure based on a space cable mesh reflector antenna. The lightweight thermoelectric conversion device of the PDS is reasonably considered. Thereafter, a TER solar tracker (specifically, 3-RPS) is mainly selected and designed for the PDS. Through an inverse kinematic analysis of the tracker, a sun-tracking control strategy of height variation is employed to reduce the number of sections in each extensible rod from three to two and to decrease total energy consumption. Meanwhile, a compound joint consisting of hook and rotary joints is substituted for the spherical joint of the solar tracker to overcome its inadequate rotational range and facilitate fabrication. By setting the PDS to an extreme orientation and subjecting it to wind and gravitational loads, its structural parameters are further determined through analysis and optimization. Although the surface density of the PDS is only approximately 1 kg/m2, the system performs satisfactorily even when subjected to loads. The dynamic model of the PDS is established by the Newton–Euler formulation. The power requirement of the PDS is determined through the dynamic analysis; it is found that during winter solstice, its maximum power is only 0.024 W, and the daily energy consumption is only 210.05 J. Finally, sun-tracking experiments on the TER solar tracker are performed to verify the theoretical and simulation analysis results; the sun-tracking accuracy is estimated to be within ±0.7°, which satisfies the PDS requirement although the machining precision of its components is not high.

Active Shape Adjustment of Large Cable-Mesh Reflectors Using Novel Fast Model Predictive Control

AbstractActive shape adjustment of a cable-mesh reflector is a significant procedure to compensate the effects of a complicated space environment in orbit. In this paper, the active shape adjustmen...

Model Reduction of Cable Mesh Reflector Antennas With Integrated Structural-Electromagnetic Criterion

A modal truncation method based on an integrated structural-electromagnetic criterion is proposed for model reduction of cable mesh reflector antennas. Combining structural dynamic characteristics and approximate electrical field calculation, a nonlinear time-invariant state-space representation is established for the integrated structural-electromagnetic system model. Incorporating structural modal analysis into electromagnetic sensitivity computation, an evaluation factor defined as the product of effective mass fraction and electromagnetic sensitivity with respect to modal coordinates is presented to simplify the complex model. It can reduce the order of finite element model directly orientating to the electromagnetic performance with acceptable accuracy. An offset cable mesh reflector and a boom are employed in this method to show its feasibility and effectiveness in modal truncation.

Surface Design Method Incorporating Compression Members for Cable-Mesh Reflectors

The tension truss antenna structure is an effective architecture for large and high-precision parabolic reflectors. Here a parabolic surface is approximated by planar triangular facets formed using cables. However, as the surface area increases or the required accuracy increases, the stiffness of the support structure must also increase to prevent its deformation under the increasing strain energy in the cables. This paper proposes a new conceptual cable network for forming parabolic surfaces with low strain energy. Instead of cables, compression members are installed at the rim of the surface so that the strain energy of the cable network is reduced. In this concept, a weight reduction of approximately 25% is possible for the support structure. This design is compared with a conventional cable network, and it is shown that the proposed design is useful in constructing higher-accuracy surface antennas and larger antenna reflectors with lower weight.

Design of shaped offset cable mesh reflector antennas considering structural flexible property

Contoured beams are required in the next design period of cable mesh reflector antennas. This study presents a new approach for synthesising contoured beams by integrated structural-electromagnetic optimisation concept. A multidisciplinary optimisation model is established from the viewpoint of interaction between structural and electromagnetic disciplines. The structural parameters are directly optimised to produce contoured beams. To consider the structural flexible property, sensitivity analysis of radiation pattern with respect to surface nodal displacements and further to structural parameters is performed in the approach. With both the information of structural and electromagnetic sensitivities, the optimisation model is expanded and solved by a sequential linear programming. Simulation results of a contoured beam covering the continental United States (CONUS) verify its effectiveness.

Two-step Structural Design of Mesh Antennas for High Beam Pointing Accuracy

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, circular 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 implemented 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 Broyden-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 0.0001º of electromagnetic performance is achieved.

Form-finding design of cable-mesh reflector antennas with minimal length configuration

Deployable cable-mesh reflector antenna is one popular kind of satellite antennas for space applications. The form-finding design of cable-mesh antennas, which aims to determine the pre-tensioned equilibrium state with a satisfactory reflector surface shape, is vital and indispensable. The tension uniformity of the cables plays an important role in maintaining the stability of the surface shape of on-orbit cable-mesh antennas. A new iterative form-finding technique based on force density method is presented to implement the uniform-tension design of cable-mesh antennas. First, equilibrium equations of the front, the rear and the whole cable nets are derived based on force density method. Then, based on the equilibrium equations, an iterative form-finding strategy is proposed. In the design process, force densities of all the cables are updated simultaneously to achieve the uniform tension of the front and rear nets, and node positions of the front net are iteratively modified to ensure that they are exactly located on the paraboloid. Finally, three typical cable-mesh antennas are employed to illustrate the feasibility and effectiveness of the method. Simulation results show that the front and rear cable nets of the obtained cable-mesh antennas are both minimal length configurations with the tension ties being inclined appropriately.

Uniform-tension form-finding design for asymmetric cable-mesh deployable reflector antennas

Space antennas with high gain and high directivity are in great demand for future communication and observation applications. Deployable cable-mesh reflector antennas are required to be tensioned in a self-equilibrated state through form-finding design. In order to ensure the cable-mesh reflector antennas’ high performances, both surface accuracy requirements and tension uniformity should be considered in the form-finding design process. To effectively implement the form-finding design for asymmetric cable-mesh antennas, a two-step uniform-tension form-finding approach is presented. In step 1, with the cable tension and membrane stress being considered simultaneously, an iterative design technique which combines force density method and surface stress density method is presented. In step 2, considering the asymmetry between the rear and front nets, the nodal z-coordinates and cable tensions of the rear net are designed with the combination of the equilibrium matrix method and force density method. Finally, an offset AstroMesh antenna is designed using the proposed method. For the obtained antenna, the cable tension and membrane stress of the front net are completely uniform, and the maximum tension ratio of the rear cable net is 1.06, which are very satisfactory.

A combined shape control procedure of cable mesh reflector antennas with optimality criterion and integrated structural electromagnetic concept

A combined shape control procedure with optimality criterion and integrated structural electromagnetic concept for cable mesh reflector antennas is presented in this study. Using the optimality criterion, the shape control algorithm drives the distorted surface towards the ideal shape. The optimality criterion is implemented by pseudo inverse of sensitivity matrix of surface nodal displacements with respect to cable member dimensions to accelerate the iterative convergence. The following integrated structural electromagnetic design is performed to make good electromagnetic performance by a sequential quadratic programming optimization model. A distorted offset cable mesh reflector antenna is employed to show its effectiveness.

Integrated Structural Electromagnetic Analysis of Mesh Reflectors with Structural Random Dimensional Errors

A new procedure for the integrated structural electromagnetic analysis of cable mesh reflectors with structural random dimensional errors is presented. The procedure combines the integrated structural electromagnetic analysis with reliability analysis and aims to investigate the effects of structural random dimensional errors on the antenna far-field directivity pattern. Both the antenna far-field directivity pattern and structural member dimensions are taken as random variables in this procedure. The computational expressions of the mean value and variance of the far-field directivity are developed by means of the random factor method and the random variable’s functional moment method. The influences of structural random dimensional errors on the randomness of radiation directivity pattern are inspected via an offset cable mesh reflector.