Flexible Electromagnetic Absorption Sheet for Millimeter-Wave Matching
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Solution Overview
Problem
Existing electromagnetic-wave absorbing sheets lack sufficient flexibility to effectively absorb high-frequency electromagnetic waves above the millimeter-wave band.
Innovation Solution
An electromagnetic-wave absorbing sheet is developed with a magnetic iron oxide-based electromagnetic-wave absorbing layer and a non-magnetic dielectric layer, which allows for magnetic resonance absorption of high-frequency electromagnetic waves and provides flexibility through the use of a rubber binder and a dielectric layer with specific permittivity and thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a sheet-shaped electromagnetic-wave absorbing sheet is designed to have flexibility using a rubber binder, then flexibility and ease of handling are improved, but the ability to absorb high-frequency electromagnetic waves (millimeter-wave band and above) deteriorates
Solution Approach 1:
The patent uses a composite material consisting of epsilon iron oxide particles (electromagnetic wave absorbing material) dispersed in a rubber binder matrix. This composite structure allows the material to simultaneously exhibit the high-frequency absorption properties of epsilon iron oxide and the flexibility of rubber, resolving the contradiction between flexibility and absorption capability.
Solution Approach 2:
The patent optimizes specific parameters including the particle size distribution of epsilon iron oxide (0.1-10 μm), the volume concentration (30-70 vol%), and the rubber binder composition to achieve both flexibility and high-frequency absorption. By carefully controlling these parameters, the material maintains rubber-like flexibility while preserving the electromagnetic wave absorption characteristics.
2Reliability
If epsilon iron oxide particles are used to absorb millimeter-wave band electromagnetic waves, then high-frequency absorption is improved, but the sheet loses flexibility and becomes rigid
Solution Approach 1:
The patent forms a flexible sheet structure where epsilon iron oxide particles are embedded in a continuous rubber binder matrix. This configuration allows the sheet to maintain flexibility despite containing rigid particles, as the rubber matrix provides the flexible framework that allows bending and deformation while the particles remain suspended within it.
Solution Approach 2:
The patent creates local regions with different properties: the rubber binder provides flexibility and elasticity, while the epsilon iron oxide particles provide electromagnetic wave absorption. This spatial distribution of different functional materials allows the sheet to exhibit both flexibility and absorption capability simultaneously in different locations.
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 sheet achieves high-frequency electromagnetic wave absorption and impedance matching, ensuring effective absorption of waves in the millimeter-wave band and above, while maintaining flexibility for easy handling and adaptation to curved surfaces.
Implementation Method 1
electromagnetic-wave absorbing material that magnetically resonates in a high-frequency band in or above a millimeter-wave band
Implementation Method 2
a non-magnetic dielectric layer is arranged on the back surface of the electromagnetic-wave absorbing layer
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An electromagnetic-wave absorbing sheet is realized which can favorably absorb electromagnetic waves with a high frequency in or above a millimeter-wave band, and has sufficient elasticity. The electromagnetic-wave absorbing sheet includes: an electromagnetic-wave absorbing layer 1 that includes a particulate electromagnetic-wave absorbing material 1a and a rubber binder 1b; and a dielectric layer 2 arranged on a back surface of the electromagnetic-wave absorbing layer. The electromagnetic-wave absorbing material is a magnetic iron oxide that magnetically resonates in a frequency band that is at least a millimeter-wave band. The dielectric layer is non-magnetic and has flexibility, a real part of a complex relative permittivity of the dielectric layer is 2 or more and 6 or less, and the dielectric layer has a thickness of 10 µm or more and 100 µm or less.