Linear Radio Wave Absorber Structure for Angled-Incidence Noise Reduction

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Solution Overview

Problem

Existing radio wave absorbers are insufficient in absorbing radio waves incident at angles, leading to inadequate noise reduction in electronic equipment.

Innovation Solution

A radio wave absorber design featuring a support with a linear absorber portion that has a maximum length on its cross-section of 25% or less of the radio wave wavelength and an occupancy of 0.05 to 0.70, incorporating a radio wave absorption material and a binder, which reduces scattering and enhances absorption across various angles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a metal plate or shielding material is used to prevent radiation noise leakage, then the shielding effect is improved, but irregular reflection of electromagnetic waves occurs causing malfunctions in electronic equipment

Engineering Contradiction:
Improveradiation noise leakageVSAvoidreflected electromagnetic wave
Core Design Contradiction:
Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful reflected electromagnetic waves into beneficial absorbed energy by using a radio wave absorber made of foam material with specific electrical resistance (0.01-10 Ω·m) and thickness (0.01-0.1 times the wavelength). This transforms the shielding approach from reflection-based (harmful) to absorption-based (beneficial), eliminating malfunctions while maintaining noise prevention

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the key parameters of the absorber material: electrical resistance is optimized to 0.01-10 Ω·m and thickness to 0.01-0.1 times the wavelength. These parameter adjustments enable effective absorption across different frequency bands while preventing irregular reflection, resolving the contradiction between shielding effectiveness and electromagnetic wave reflection

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If a radio wave absorber with larger size is used to improve absorption effectiveness, then the absorption capability is improved, but the device complexity and space requirements increase

Engineering Contradiction:
Improveradio wave absorption effectivenessVSAvoidabsorber structure complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent optimizes the thickness parameter to 0.01-0.1 times the wavelength of the target radio wave frequency, enabling thin absorber designs that maintain high absorption effectiveness without increasing device complexity. This parameter optimization allows effective noise reduction in compact electronic equipment

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses foam material with controlled electrical resistance (0.01-10 Ω·m), creating a composite structure that achieves effective absorption in thin profiles. The foam's inherent porosity combined with specific electrical properties enables high absorption capability without increasing size or structural complexity

Inventive Principle:
Principle #40Composite materials

3Object-affected harmful factors

If the electrical resistance of the absorber material is increased to improve absorption, then the absorption capability is improved, but the material selection and manufacturing complexity increase

Engineering Contradiction:
Improveradio wave absorption capabilityVSAvoidmaterial selection complexity
Core Design Contradiction:
Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent defines a specific electrical resistance range (0.01-10 Ω·m) that balances absorption capability with manufacturing ease. This parameter specification enables selection from common conductive foam materials while achieving effective absorption, simplifying the manufacturing process

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs foam material that can be manufactured with controlled electrical resistance through standard processes. The foam structure allows easy adjustment of electrical properties during manufacturing, making it easier to produce absorbers with optimal absorption characteristics without complex material selection

Inventive Principle:
Principle #40Composite materials

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 design achieves excellent radio wave absorbability, as evidenced by a return loss of 20.0 dB or higher at 45° incidence angle and 48 GHz, effectively mitigating the impact of incidence angles and improving noise reduction in electronic equipment.

Implementation Method 1

a dielectric constant of 3.0 or more and a loss tangent of 0.30 or more at 10 GHz

Methodology Applied
Scientific EffectDielectric loss: Dielectric Heating

Implementation Method 2

an electrical resistance in a range of 0.01 Ω·m to 10 Ω·m

Methodology Applied
Scientific EffectConductive loss: Joule Heating

Data Source

PatentEP3606308B1Electromagnetic wave absorber and method for producing electromagnetic wave absorber
Publication Date: 2023.11.15 FUJIFILM CORP
  • EP3606308B1 patent drawingFigure 1
  • EP3606308B1 patent drawingFigure 2
  • EP3606308B1 patent drawingFigure 3

AI summary

A radio wave absorber including: a support; and a linear absorber that is disposed on at least one surface of the support, has an occupancy per unit volume on the support of 0.05 to 0.70, includes a radio wave absorption material and a binder, and has a maximum length on a cross section perpendicular to a longitudinal direction of 25% or less of a wavelength of the radio wave, and a manufacturing method thereof.