Collapsible AMC Antenna Structure Using Shape Memory Metal
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Solution Overview
Problem
Traditional antennas over ground planes require a quarter wavelength spacing, resulting in a thick profile, especially at low frequencies, and artificial magnetic conductor (AMC) antennas, while thinner, are stiff and cumbersome for transportation and deployment, particularly for large aperture antennas below 1 GHz.
Innovation Solution
An AMC antenna apparatus with a flexible antenna element layer and a ground plane featuring a conductive base surface, a frequency selective surface (FSS) layer, and memory metal wires that are rigid during operation but flexible for stowage, allowing the FSS layer to collapse towards the base surface, facilitated by a retaining structure and actuators for deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional quarter-wavelength spacing is used, then directivity performance is achieved, but antenna profile becomes thick
Solution Approach 1:
The patent changes the electromagnetic boundary conditions at the ground plane by introducing an artificial magnetic conductor (AMC) structure with frequency selective surface and memory metal wires. This transforms the traditional quarter-wavelength spacing requirement into a much smaller spacing configuration while maintaining directivity performance through altered electromagnetic field interaction.
Solution Approach 2:
The ground plane employs a composite structure combining conductive base surface, frequency selective surface with conductive patches, and memory metal wires. This composite design creates artificial magnetic conductor properties that enable thin profile operation while preserving antenna performance.
2Length of stationary object
If AMC ground plane with FSS and conductive patches is used, then antenna thickness is reduced, but structural stiffness becomes cumbersome for transport
Solution Approach 1:
The memory metal wires provide dynamic mechanical properties, transitioning from a rigid state during operation to a flexible state during stowage and transport. This allows the antenna to be thin and stiff when needed for performance, yet flexible and easy to handle when needed for deployment and storage.
Solution Approach 2:
The memory metal wires change their mechanical parameters (rigidity/flexibility) in response to temperature changes. Below a threshold temperature, the wires become flexible enabling collapse and stowage; above the threshold, they become rigid maintaining the operational antenna structure.
3Volume of moving object
If memory metal wires are made flexible for stowage, then compact storage is enabled, but structural integrity during operation may be compromised
Solution Approach 1:
The memory metal wires exhibit temperature-dependent parameter changes in their mechanical properties. At low temperatures, they are flexible enough to allow collapse to a compact state for stowage; at operational temperatures, they become rigid enough to maintain the precise spacing and structural integrity required for antenna function.
Solution Approach 2:
The memory metal wires undergo a phase transition or state change based on temperature, transforming from a flexible martensitic phase during stowage to a rigid austenitic phase during operation. This phase transition ensures both compact stowage capability and operational structural integrity.
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
Enables a significantly thinner antenna design with efficient directivity performance and facilitates compact stowage and transportation by automatically expanding to operational configuration upon ambient temperature threshold, ensuring effective deployment and operation.
Implementation Method 1
The memory metal wires automatically transform from flexible to rigid states when ambient temperature exceeds a threshold
Data Source
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AI summary
An artificial magnetic conductor (AMC) antenna apparatus includes a ground plane and a flexible antenna element layer above the ground plane. The ground plane includes a conductive base surface, a plurality of memory metal wires, and a frequency selective surface (FSS) layer above the base surface, where the FSS layer includes a plurality of conductive patches separated from one another. Each of the memory metal wires electrically connects one of the conductive patches to the base surface. Each of the memory metal wires is rigid in a memory-shaped state, causing the FSS layer to be fixedly spaced from the base surface during operation of the AMC antenna apparatus. The memory metal wires are each flexible in a non-memory-shaped state, enabling the FSS layer to be collapsed towards the base surface when the antenna apparatus is stowed.