Hexagonal Ferrite Radio Wave Absorber With Controlled Squareness Ratio

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Solution Overview

Problem

Conventional radio wave absorbers containing hexagonal ferrite and a binder do not consistently exhibit sufficient radio wave absorbability.

Innovation Solution

A radio wave absorber comprising a powder of substitution-type magnetoplumbite-type hexagonal ferrite, where a part of iron atoms are substituted with aluminum atoms, and a binder, with a squareness ratio ranging from 0.40 to 0.60, enhancing radio wave absorbability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional hexagonal ferrite powder and binder are used, then workability into desired shape is improved, but radio wave absorbability is insufficient

Engineering Contradiction:
Improveworkability into desired shapeVSAvoidradio wave absorbability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The invention changes the magnetic parameters of the hexagonal ferrite powder by controlling the squareness ratio to be 0.25 or less. This parameter change allows the material to maintain good radio wave absorbability while being processable with conventional binders into desired shapes, thus resolving the contradiction between workability and absorbability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite material system consisting of hexagonal ferrite powder with specific magnetic properties (squareness ratio ≤ 0.25) combined with conventional binders. This composite approach enables both good workability for shaping and sufficient radio wave absorbability, as the optimized powder properties compensate for the presence of the binder.

Inventive Principle:
Principle #40Composite materials

2Reliability

If high frequency band absorbability is improved, then transmission attenuation is enhanced, but manufacturing precision of magnetic properties becomes more difficult to control

Engineering Contradiction:
Improveradio wave absorbability in high frequency bandsVSAvoidcontrol of magnetic properties
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The invention identifies the squareness ratio as a key parameter that directly influences high-frequency absorbability. By setting the squareness ratio to 0.25 or less, the invention achieves good radio wave absorbability in high frequency bands while providing a clear, controllable manufacturing target that simplifies rather than complicates the control of magnetic properties.

Inventive Principle:
Principle #35Parameter changes

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 proposed absorber achieves excellent radio wave absorbability in high frequency bands, improving the alignment of easily magnetizable axes and maintaining good crystallinity, thereby enhancing transmission attenuation.

Implementation Method 1

a radio wave absorber including a powder of a hexagonal ferrite and a binder, in which the radio wave absorber has a squareness ratio in a range of 0.40 to 0.60

Methodology Applied
Scientific EffectMagnetic loss: Magnetic Hysteresis

Implementation Method 2

improving the alignment of easily magnetizable axes

Methodology Applied
Scientific EffectMagnetic anisotropy: Anisotropy

Data Source

PatentEP3971245B1Radio wave absorber
Publication Date: 2026.02.18 FUJIFILM CORP

AI summary

There is provided a radio wave absorber including a powder of a hexagonal ferrite; and a binder, in which the radio wave absorber has a squareness ratio in a range of 0.40 to 0.60.