Deployable Mesh Reflectors with Adjustable Tensioning
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Solution Overview
Problem
Existing deployable mesh reflectors for spacecraft antennas face challenges in maintaining uniform tension, minimizing passive inter-modulation (PIM) and electrostatic discharge (ESD), and efficiently packaging to form optimally-shaped reflector surfaces without increasing mass or complexity, especially when using gold-plated molybdenum wire meshes.
Innovation Solution
A system and method for fabricating a deployable umbrella-style reflector using a soft wire mesh with a novel edge treatment that is lightweight, low stiffness, and low coefficient of thermal expansion, which maintains uniform tension and minimizes PIM and ESD, while allowing for arbitrary shaping with tension-only and tension/compression members to control curvature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a soft wire mesh is used to form the reflective surface, then the reflector can be efficiently packaged and deployed in space, but maintaining uniform tension in the mesh becomes difficult
Solution Approach 1:
The patent applies parameter changes by carefully selecting and controlling the mesh properties (wire diameter, mesh opening size, material composition) and tensioning parameters (pre-tension levels, distribution patterns) to achieve both efficient packaging and uniform tension maintenance in the deployable mesh reflector
Solution Approach 2:
The patent employs dynamic tensioning mechanisms that can adjust and maintain uniform tension across the mesh surface during deployment and operation, allowing the mesh to transition from a compact packaged state to a fully deployed reflective surface while maintaining proper tension distribution
2Ease of manufacture
If traditional mesh edge treatment is used, then the mesh can be terminated, but passive inter-modulation (PIM) and electrostatic discharge (ESD) are generated
Solution Approach 1:
The patent replaces traditional metallic mesh edge treatments with a non-conductive coating or alternative material termination that eliminates PIM and ESD generation at the mesh edges, using materials that are electrically isolating yet mechanically sufficient for edge support
Solution Approach 2:
The patent converts the potentially harmful metallic edges into beneficial non-conductive edges by applying specialized coatings or using alternative materials, transforming the edge treatment from a source of PIM and ESD into a component that actively prevents these harmful effects while maintaining structural integrity
3Shape
If the mesh is attached to the net structure, then the mesh can be maintained in shape, but the attachment affects the shape and tension levels of the net structure
Solution Approach 1:
The patent introduces intermediary attachment mechanisms or transition layers between the mesh and net structure that distribute loads more evenly, reducing the direct impact of mesh attachment on the net structure's tension distribution and shape stability
Solution Approach 2:
The patent optimizes attachment parameters such as attachment point spacing, attachment method (sewing, bonding, mechanical fastening), and pre-tension levels to minimize the influence of mesh attachment on the net structure while maintaining proper mesh shape and tension
4Reliability
If gold-plated molybdenum wire mesh is used, then RF performance is improved, but mass and complexity increase
Solution Approach 1:
The patent optimizes the mesh parameters including wire diameter, mesh opening size, and material composition to achieve the necessary RF performance with minimized mass, carefully balancing the gold plating thickness and molybdenum wire specifications to meet performance requirements while reducing weight
Solution Approach 2:
The patent applies gold plating only where necessary for RF performance (partial action) rather than coating the entire mesh structure uniformly, or uses alternative materials with sufficient RF properties that require less mass to achieve the same performance level
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables the creation of shaped reflectors with both positive and negative curvatures, maintaining uniform tension and minimizing the impact on the net structure's shape and tension levels, reducing mass and complexity, and preventing PIM and ESD, thus enhancing RF performance and deployment efficiency.
Implementation Method 1
A soft knitted mesh fabricated out of a thin metallic wire (e.g., gold-plated molybdenum wire) is commonly used to form the reflective surface of deployable radio-frequency (RF) antenna reflectors
Implementation Method 2
allowing for arbitrary shaping with tension-only and tension/compression members to control curvature
Data Source
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AI summary
A method and apparatus for making a mesh reflector that may be used to produce a shaped reflector is provided. The mesh reflector may be an umbrella-style deployable mesh reflector capable of approximating both parabolic and arbitrarily shaped reflecting surfaces, including those with regions of reversed curvature. The reflecting surface may be provided by a soft mesh attached to a highly pre-tensioned net composed of two sets of substantially parallel chords forming a plurality of parallelogram-shaped facets. The net/mesh may be made to conform to the desired shape by pulling and/or pushing on it at each of its facet corners via a set of finely adjustable tension ties and/or compression rods, the distal ends of which react against a set of pre-tensioned catenary-shaped chords disposed on the aft side of the mesh. The net/mesh and the aft catenaries may be supported and pre-tensioned by a set of substantially stiff radial ribs connected to a central hub by a means capable of providing high deployment torque and a means for controlling and coordinating the deployment of the ribs so that they reach their fully deployed positions nearly simultaneously. Methods for fabricating the mesh and attaching it to the net are also provided.