Multilayer Radar-Absorbing Polymer Parts With Low Reflection
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Solution Overview
Problem
Conventional radar absorbing materials (RAM) either prioritize absorption or reflection, failing to achieve a balance between low reflectivity and high absorption, necessitating thicker materials or software solutions to mitigate issues.
Innovation Solution
A multilayer part composed of a first layer with a thickness greater than 0.8 mm and a second layer with a thickness of 0.2 mm to 0.7 mm, each containing specific carbon-based fillers and polymers, with a dielectric constant ratio and adhesive layer in between, achieving less than 15% reflectivity and 6% transmission at frequencies from 77 GHz to 81 GHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If higher conductivity carbon-based fillers are used to improve electromagnetic wave attenuation and reduce transmission, then transmission is reduced, but reflection increases
Solution Approach 1:
The patent divides the single-layer RAM material into multiple layers with different conductivity characteristics. The first layer has higher conductivity (0.1-30 wt% carbon filler) for attenuation, while the second layer has lower conductivity (0.01-3 wt% carbon filler) for reduced reflection. This segmentation allows each layer to optimize for its specific function, resolving the contradiction between attenuation and reflection.
Solution Approach 2:
Different regions (layers) of the RAM material are assigned different local properties: the first layer near the radar source has high conductivity for strong attenuation, while the second layer farther away has low conductivity for minimal reflection. This local quality differentiation enables simultaneous optimization of both attenuation and reflection characteristics throughout the material structure.
2Object-generated harmful factors
If conventional RAM materials are used to achieve low reflectivity, then reflection is reduced, but transmission remains high requiring thicker materials
Solution Approach 1:
The patent creates a composite multilayer structure combining materials with different conductivity properties. The first layer uses high-conductivity carbon-filled polymer for attenuation, while the second layer uses low-conductivity carbon-filled polymer for reflection reduction. This composite approach achieves both low reflection and adequate attenuation in a thinner overall structure than conventional single-layer materials.
3Reliability
If higher conductivity is used to improve shielding performance, then electromagnetic wave attenuation improves, but the material becomes more conductive leading to increased reflection
Solution Approach 1:
The shielding function is segmented into two distinct layers: the first layer provides the primary shielding through high conductivity, while the second layer compensates for reflection issues through low conductivity. This segmentation allows the system to achieve reliable shielding performance without the harmful reflection effect that would occur in a single high-conductivity layer.
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 multilayer part effectively combines low reflectivity and high absorption, surpassing the performance of conventional single-layer materials, suitable for radar absorbing applications.
Implementation Method 1
a first electrically conductive carbon-based filler component... a second electrically conductive carbon-based filler component... the higher the conductivity the better the attenuation of electro-magnetic waves
Implementation Method 2
The dielectric constant (Dk) of the second layer is 2 to 5... the ratio of a Dk of the second layer to a Dk of the first layer... at frequencies of from about 77 GHz to 81 GHz
Implementation Method 3
Absorption occurs when the electromagnetic field/photons interact and transfer energy to the substance/material they are striking instead of transmitting through or reflecting it
Implementation Method 4
an intervening third layer consisting of an adhesive such that the adhesive is disposed between the first layer and the second layer
Data Source
AI summary
A multilayer part consists of: a first layer having a thickness greater than 0.8 mm consisting of a first polymer and from about 0.1 wt. % to about 30 wt. % of a first electrically conductive carbon-based filler component; a second layer disposed adjacent a surface of the first layer consisting of a second polymer composition consisting of at least a second polymer and from about 0.01 wt. % to about 3 wt. % of a second electrically conductive carbon-based filler component; and an intervening third layer consisting of an adhesive such that the adhesive is disposed between the first layer and the second layer. A ratio of a thickness of the first layer to the second layer is from 1:1 to 20:1. The first electrically conductive carbon-based filler component consists of a different filler or combination of fillers than the second electrically conductive carbon-based filler component.