JP2003193103A - Broad-band electromagnetic wave absorber for quasi- millimeter wave - Google Patents
Broad-band electromagnetic wave absorber for quasi- millimeter waveInfo
- Publication number
- JP2003193103A JP2003193103A JP2001400850A JP2001400850A JP2003193103A JP 2003193103 A JP2003193103 A JP 2003193103A JP 2001400850 A JP2001400850 A JP 2001400850A JP 2001400850 A JP2001400850 A JP 2001400850A JP 2003193103 A JP2003193103 A JP 2003193103A
- Authority
- JP
- Japan
- Prior art keywords
- electromagnetic wave
- powder
- soft magnetic
- magnetic metal
- quasi
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000006096 absorbing agent Substances 0.000 title claims abstract description 17
- 239000000843 powder Substances 0.000 claims abstract description 41
- 229910052751 metal Inorganic materials 0.000 claims abstract description 22
- 239000002184 metal Substances 0.000 claims abstract description 22
- 239000011159 matrix material Substances 0.000 claims abstract description 9
- 239000002245 particle Substances 0.000 claims abstract description 7
- 229920001971 elastomer Polymers 0.000 claims abstract description 5
- 239000004033 plastic Substances 0.000 claims abstract description 5
- 229920003023 plastic Polymers 0.000 claims abstract description 5
- 238000010521 absorption reaction Methods 0.000 claims description 11
- 239000000945 filler Substances 0.000 claims description 3
- 238000000465 moulding Methods 0.000 claims description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 2
- 150000001875 compounds Chemical class 0.000 abstract 1
- 230000035699 permeability Effects 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 6
- 230000007423 decrease Effects 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 230000001629 suppression Effects 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- 229920006235 chlorinated polyethylene elastomer Polymers 0.000 description 2
- 102100033041 Carbonic anhydrase 13 Human genes 0.000 description 1
- 101000867860 Homo sapiens Carbonic anhydrase 13 Proteins 0.000 description 1
- 101100219325 Phaseolus vulgaris BA13 gene Proteins 0.000 description 1
- 229920000800 acrylic rubber Polymers 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000006247 magnetic powder Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229920000058 polyacrylate Polymers 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
Landscapes
- Powder Metallurgy (AREA)
- Hard Magnetic Materials (AREA)
- Soft Magnetic Materials (AREA)
- Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、準ミリ波、すなわ
ち２０〜３０ＧＨｚの高周波領域において使用する、広
い帯域にわたって高い電磁波吸収能を確保した電磁波吸
収体に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave absorber which is used in a quasi-millimeter wave, that is, in a high frequency region of 20 to 30 GHz, and which has a high electromagnetic wave absorbing ability over a wide band.
【０００２】[0002]
【従来の技術】軟磁性金属の粉末をゴムまたはプラスチ
ックのマトリクス中に分散させ、通常はシート状に成形
してなるものが、電磁波吸収体として広く使用されてい
る。出願人は、この種の電磁波吸収体の研究を続け、種
々の用途に対応した製品を開発して、すでに多数を開示
している。2. Description of the Related Art A soft magnetic metal powder dispersed in a rubber or plastic matrix and usually formed into a sheet is widely used as an electromagnetic wave absorber. The applicant has continued research on this type of electromagnetic wave absorber, has developed products for various applications, and has already disclosed many.
【０００３】電磁波吸収体の用途の中には準ミリ波の領
域で使用するものが含まれており、これは、各種電子機
器で使用する周波数が高周波化する傾向により、必要に
なるものである。ところが、上記した構造の電磁波吸収
体の性能が発揮できるのは、高々１ＧＨｚ程度であり、
２０〜３０ＧＨｚという領域には及ばないのが現状であ
る。Some of the uses of the electromagnetic wave absorber include those used in the quasi-millimeter wave region, which is necessary because the frequencies used in various electronic devices tend to become higher. . However, the performance of the electromagnetic wave absorber having the above structure can be exhibited at a maximum of about 1 GHz,
At present, it does not reach the range of 20 to 30 GHz.
【０００４】この問題の解決策として、出願人は、ま
ず、高次吸収ピークすなわち第二次、第三次の吸収ピー
クを利用して高い周波数領域まで吸収性能を及ぼすこと
を提案した（特開２００１−１８９５８５）。それにつ
づいて、吸収のピークを位置させようとする周波数にお
けるシートの透磁率と誘電率の測定値に基づいて、特定
の式により表される反射減衰の値が最大になるよう、粉
末充填率とシートの厚さを選択することを提案した（特
開２００１−１８９５８６）。As a solution to this problem, the applicant first proposed that high-order absorption peaks, that is, second-order and third-order absorption peaks, are utilized to exert absorption performance up to a high frequency region (Japanese Patent Laid-Open No. 2000-242242). 2001-189585). Then, based on the measured values of the magnetic permeability and permittivity of the sheet at the frequency where the absorption peak is to be located, the powder filling factor and the powder filling factor are set so that the value of the reflection attenuation represented by a specific formula becomes maximum. It has been proposed to select the thickness of the sheet (JP 2001-189586).
【０００５】これらの対策は、特定の周波数の電磁波を
吸収するという目的を達成する上では、好成績をおさめ
た。しかし、その後、準ミリ波の領域において、特定の
周波数で鋭いピークをもった選択的な吸収でなく、ある
程度広い周波数帯域にわたって、一定レベルの吸収性能
を示す電磁波吸収が必要とされるようになった。上記の
対策は、この要望には応えられない。These measures have been successful in achieving the purpose of absorbing electromagnetic waves of a specific frequency. However, after that, in the quasi-millimeter wave region, instead of selective absorption having a sharp peak at a specific frequency, electromagnetic wave absorption showing a certain level of absorption performance over a relatively wide frequency band is required. It was The above measures cannot meet this demand.
【０００６】[0006]
【発明が解決しようとする課題】本発明の目的は、新し
い要望に応え、準ミリ波の領域において、広い帯域にわ
たって、高い電磁波吸収能を確保した電磁波吸収体を提
供することにある。SUMMARY OF THE INVENTION It is an object of the present invention to provide an electromagnetic wave absorber satisfying a new demand and ensuring a high electromagnetic wave absorbing ability over a wide band in the quasi-millimeter wave region.
【０００７】[0007]
【課題を解決するための手段】上記の目的を達成する本
発明の準ミリ波用広帯域電磁波吸収体は、軟磁性金属の
粉末をゴムまたはプラスチックのマトリクス中に分散さ
せ、シート状に成形してなる電磁波吸収体において、下
記の条件をすべて満たすことにより、（ａ）軟磁性金属
の粉末として平均粒径３μｍ以下の微粉末を使用するこ
と、（ｂ）軟磁性金属の粉末の充填率が５〜２５容積％
の範囲にあること、および（ｃ）シートの厚さが０．５
〜１．５mmの範囲にあること、準ミリ波帯において、少
なくとも５ＧＨｚの帯域にわたって反射減衰−１５ｄＢ
の吸収性能を確保した電磁波吸収体である。The quasi-millimeter wave broadband electromagnetic wave absorber of the present invention which achieves the above object is obtained by dispersing a powder of a soft magnetic metal in a matrix of rubber or plastic and molding it into a sheet. In this electromagnetic wave absorber, by satisfying all of the following conditions, (a) using a fine powder having an average particle diameter of 3 μm or less as the soft magnetic metal powder, and (b) filling the soft magnetic metal powder with a filling factor of 5 ~ 25% by volume
And (c) the sheet has a thickness of 0.5.
In the range of up to 1.5 mm, in the quasi-millimeter wave band, the return loss is -15 dB over at least 5 GHz.
It is an electromagnetic wave absorber that secures the absorption performance of.
【０００８】[0008]
【発明の実施形態】軟磁性金属の粉末として、本発明で
は平均粒径３μｍ以下という微粉末を使用する。その必
要は、後記する実施例と比較例との対比から理解できる
であろう。金属粉末の製造技術として常用されている噴
霧法では、このような微粉末の製造は容易でなく、噴霧
粉をさらに微細化する必要があるが、それには多大なエ
ネルギーを必要とし、しかも効率が低いから、むしろ、
カルボニル鉄粉末のように、高価ではあるが、それ自体
が本来微粉末を与える製造法による粉末を選択する方が
賢明である。BEST MODE FOR CARRYING OUT THE INVENTION As the soft magnetic metal powder, fine powder having an average particle diameter of 3 μm or less is used in the present invention. The necessity can be understood from the comparison between the example and the comparative example described later. In the spraying method which is commonly used as a manufacturing technique for metal powders, it is not easy to manufacture such fine powders, and it is necessary to further miniaturize the sprayed powders, but this requires a large amount of energy and is more efficient. Rather low,
It is prudent to choose a powder, such as carbonyl iron powder, which is expensive but which by its own process gives itself a fine powder.
【０００９】粉末を分散させるマトリクス材料は、常用
の塩素化ポリエチレンゴムが使いやすいが、耐熱性を要
求される場合は、アクリルゴムなど、それに適したもの
を選択する。そのほか、シートへの成形は、電磁波抑制
体の分野で既知の技術にしたがって実施すればよい。軟
磁性金属の粉末をマトリクス材料中に均一に分散させる
ことは、粉末が微細になるほど容易でなくなるから、た
とえば後記の実施例で行なっているような、軟磁性金属
の粉末に加え、電磁波に対して不活性な粉末充填剤を５
０容積％以下の量添加するなど、均一な分散を助ける手
法を採用することが推奨される。As the matrix material for dispersing the powder, a commonly used chlorinated polyethylene rubber is easy to use. However, when heat resistance is required, an appropriate material such as acrylic rubber is selected. In addition, molding into a sheet may be performed according to a technique known in the field of electromagnetic wave suppressors. Since it is not easy to uniformly disperse the soft magnetic metal powder in the matrix material as the powder becomes finer, for example, in addition to the soft magnetic metal powder as performed in Examples described later, the 5 inert powder filler
It is recommended to adopt a method of helping uniform dispersion, such as adding an amount of 0% by volume or less.
【００１０】微粉末の使用（ａ）とともに本発明の要件
である、軟磁性金属の粉末の充填率が５〜２５容積％の
範囲にあること（ｂ）と、シートの厚さが０．５〜１．
５mmの範囲にあること（ｃ）とは、広い帯域にわたる吸
収能を実現する上で必要な要件であることが、やはり経
験的に知られた事項である。これらの範囲内で各要件を
適切に選択することにより、後記する実施例に見るよう
に、吸収される周波数帯域が若干異なる電磁波抑制シー
トを製作することができる。Along with the use of fine powder (a), the filling factor of the soft magnetic metal powder, which is a requirement of the present invention, is in the range of 5 to 25% by volume (b), and the sheet thickness is 0.5. ~ 1.
It is also empirically known that the fact that the thickness is in the range of 5 mm (c) is a requirement necessary for realizing the absorption capacity over a wide band. By appropriately selecting each requirement within these ranges, it is possible to manufacture an electromagnetic wave suppression sheet having a slightly different frequency band to be absorbed, as will be seen in Examples described later.
【００１１】軟磁性金属の粉末を分散させた構造の電磁
波抑制体が有効に作用する機構は、まだ十分に解明され
ていないが、電磁波抑制体の示す透磁率が磁束の封じ込
め効果をもたらすとか、透磁率がインダクタンス成分Ｌ
（透磁率の実部μ’）やリアクタンス成分Ｒ（透磁率の
虚部μ''）として、ノイズ電磁波発生のメカニズムに抑
制的に働くのではないか、という議論がなされている。The mechanism by which the electromagnetic wave suppressor having the structure in which the powder of the soft magnetic metal is dispersed effectively works has not been fully clarified yet, but the magnetic permeability of the electromagnetic wave suppressor has the effect of confining magnetic flux. Permeability is inductance component L
It is argued that (real part of magnetic permeability μ ′) and reactance component R (imaginary part of magnetic permeability μ ″) may suppressively act on the mechanism of noise electromagnetic wave generation.
【００１２】軟磁性金属の粉末をマトリクス中に分散さ
せた電磁波抑制体について、透磁率の周波数特性を調べ
てみると、一般に、実部（μ’）はある周波数までほぼ
一定値を保ち、その周波数を過ぎた高周波側では、徐々
に低下する傾向を示す。一方、虚部（μ''）は、実部の
値が低下する周波数前後から次第に大きくなり、ピーク
値をもった後、徐々に低下するという傾向である。Regarding the electromagnetic wave suppressor in which the powder of the soft magnetic metal is dispersed in the matrix, the frequency characteristic of the magnetic permeability is examined. Generally, the real part (μ ') keeps a substantially constant value up to a certain frequency, On the high frequency side beyond the frequency, it tends to gradually decrease. On the other hand, the imaginary part (μ ″) tends to gradually increase from around the frequency where the value of the real part decreases, has a peak value, and then gradually decreases.
【００１３】図１は、後記する実施例１と比較例１の電
磁波抑制シートについて、２０〜３０ＧＨｚにおける透
磁率の変化を測定したグラフである。実施例の透磁率の
実部は、２０ＧＨｚ以下の領域では、（グラフには示し
てないが）２０ＧＨｚにおける値より低く、次第に上昇
してから低下する傾向がわかる。虚部は、実部がピーク
を迎える周波数では低く、実部の値が低下を始めたとこ
ろで、入れ替わるように上昇している。一方、比較例の
透磁率は、グラフに表われた範囲では低下の一途をたど
っており、実部も虚部も、ともにピークを過ぎたことが
うかがわれる。FIG. 1 is a graph showing changes in magnetic permeability at 20 to 30 GHz for the electromagnetic wave suppressing sheets of Example 1 and Comparative Example 1 described later. It can be seen that the real part of the magnetic permeability of the example is lower than the value at 20 GHz (not shown in the graph) in the region of 20 GHz or less, and gradually increases and then decreases. The imaginary part is low at the frequency at which the real part reaches its peak, and rises so as to be replaced when the value of the real part starts to decrease. On the other hand, the magnetic permeability of the comparative example keeps decreasing in the range shown in the graph, and it can be seen that both the real part and the imaginary part have passed the peaks.
【００１４】このような透磁率のピークは、軟磁性金属
の粉末の自然共鳴によるピークであろうと、発明者らは
推測している。粉末の粒径が大きいと、渦電流の影響を
受けて透磁率が低い周波数においてすでに低下してしま
い、ピークは現れない。本発明では平均粒径３μｍ以下
という微細な粉末を使用することにより、準ミリ波帯ま
で渦電流の影響をなくすことができ、その結果、本来の
自然共鳴による透磁率のピークが現れたものと解され
る。The present inventors presume that such a peak of magnetic permeability may be a peak due to natural resonance of the soft magnetic metal powder. If the particle size of the powder is large, it is affected by the eddy current, and the magnetic permeability is already reduced at a low frequency, and no peak appears. In the present invention, by using a fine powder having an average particle size of 3 μm or less, it is possible to eliminate the influence of eddy current up to the quasi-millimeter wave band, and as a result, the peak of magnetic permeability due to the natural resonance appears. Be understood.
【００１５】図１の実施例１の電磁波抑制シートが好成
績であった事実から、透磁率の実部と虚部とが、大きな
周波数間隔を隔ててピークを有するような製品が、広い
帯域にわたる吸収性能を示すものと考えられる。上述し
た軟磁性粉末の平均粒径の要件（ａ）に加え、粉末充填
率の要件（ｂ）およびシート厚さの要件（ｃ）を満たす
ことにより、好ましい透磁率の特性が実現する。From the fact that the electromagnetic wave suppression sheet of Example 1 in FIG. 1 was successful, a product in which the real part and the imaginary part of the magnetic permeability have peaks at large frequency intervals is absorbed over a wide band. It is considered to show performance. In addition to the requirement (a) of the average particle diameter of the soft magnetic powder described above, the requirement (b) of the powder filling rate and the requirement (c) of the sheet thickness satisfy the desirable magnetic permeability characteristics.
【００１６】[0016]
【実施例】下記の表に掲げた軟磁性金属粉末を使用し、
マトリクス材料としては塩素化ポリエチレンゴムを選
び、不活性充填剤として炭酸カルシウム粉末を加えた配
合物を、それぞれ記載の厚さのシートに圧延した。得ら
れた３種の電磁波抑制シートについて、導波管法によ
り、２０〜３０ＧＨｚの領域における反射減衰の値を測
定した。[Example] Using the soft magnetic metal powder listed in the following table,
Chlorinated polyethylene rubber was chosen as the matrix material, and the formulation with calcium carbonate powder added as an inert filler was rolled into sheets of the indicated thickness. The values of reflection attenuation in the region of 20 to 30 GHz were measured for the obtained three types of electromagnetic wave suppression sheets by the waveguide method.
【００１７】 [0017]
【００１８】結果は、図２のグラフに示すとおりであっ
て、−１５ｄＢの反射減衰が得られたのは、比較例では
２４〜２８ＧＨｚの、広さ５ＧＨｚの帯域に止まった
が、実施例１では２２〜３０ＧＨｚと、９ＧＨｚの幅、
実施例２では２１〜２８ＧＨｚと、８ＧＨｚの幅が確保
できた。The results are shown in the graph of FIG. 2. The return loss of -15 dB was obtained in the comparative example in the band of 24-28 GHz and the width of 5 GHz, but in Example 1. Then 22 ~ 30GHz and 9GHz width,
In Example 2, the widths of 21 to 28 GHz and 8 GHz could be secured.
【００１９】[0019]
【発明の効果】本発明に従って軟磁性金属の粉末をゴム
またはプラスチックのマトリクス中に分散させた電磁波
抑制シートを製作すれば、準ミリ波帯と呼ばれる２０〜
３０ＧＨｚの高周波領域において、ピークが２カ所ある
電磁波吸収性能をもち、二つのピークの間とその前後に
わたって高い反射減衰が実現するから、帯域幅にして８
〜９ＧＨｚという広い範囲の電磁波抑制が可能になる。According to the present invention, when an electromagnetic wave suppressing sheet in which a powder of a soft magnetic metal is dispersed in a rubber or plastic matrix is produced, it is called a quasi-millimeter wave band.
In the high frequency region of 30 GHz, it has electromagnetic wave absorption performance with two peaks, and high reflection attenuation is realized between the two peaks and before and after it, so that the bandwidth is 8
It is possible to suppress electromagnetic waves in a wide range of up to 9 GHz.
【図１】 本発明の電磁波抑制シートの作用機構を説明
するための、実施例と比較例との、２０〜３０ＧＨｚに
おける透磁率の変化を示すグラフ。FIG. 1 is a graph showing a change in magnetic permeability at 20 to 30 GHz of an example and a comparative example for explaining a function mechanism of the electromagnetic wave suppression sheet of the present invention.
【図２】 本発明の実施データであって、実施例と比較
例の電磁波抑制シートについて、２０〜３０ＧＨｚにお
ける反射減衰を示すグラフ。FIG. 2 is a graph showing the return loss at 20 to 30 GHz for the electromagnetic wave suppression sheets of the example and the comparative example, which is the implementation data of the present invention.
───────────────────────────────────────────────────── フロントページの続き Ｆターム(参考） 4K018 AA24 BA13 BB04 JA30 KA43 5E040 CA13 5E321 BB21 BB32 BB53 GG05 ─────────────────────────────────────────────────── ─── Continued front page F-term (reference) 4K018 AA24 BA13 BB04 JA30 KA43 5E040 CA13 5E321 BB21 BB32 BB53 GG05
Claims (3)
ックのマトリクス中に分散させ、シート状に成形してな
る電磁波吸収体において、下記の条件をすべて満たすこ
とにより、（ａ）軟磁性金属の粉末として平均粒径３μ
ｍ以下の微粉末を使用すること、（ｂ）軟磁性金属の粉
末の充填率が５〜２５容積％の範囲にあること、および
（ｃ）シートの厚さが０．５〜１．５mmの範囲にあるこ
と、準ミリ波帯において、少なくとも５ＧＨｚの帯域に
わたって反射減衰−１５ｄＢの吸収性能を確保した準ミ
リ波用広帯域電磁波吸収体。1. An electromagnetic wave absorber formed by dispersing a soft magnetic metal powder in a rubber or plastic matrix, and molding the sheet into a sheet, so that (a) the soft magnetic metal powder is satisfied. As an average particle size of 3μ
using a fine powder of m or less, (b) the filling rate of the soft magnetic metal powder is in the range of 5 to 25% by volume, and (c) the sheet has a thickness of 0.5 to 1.5 mm. A broadband electromagnetic wave absorber for the quasi-millimeter wave, which has an absorption performance of reflection attenuation of -15 dB over the band of at least 5 GHz in the quasi-millimeter wave band.
末を使用した請求項１の準ミリ波用広帯域電磁波吸収
体。2. The broadband electromagnetic wave absorber for quasi-millimeter wave according to claim 1, wherein carbonyl iron powder is used as the soft magnetic metal powder.
して不活性な粉末充填剤を５０容積％以下の量添加した
請求項１の準ミリ波用広帯域電磁波吸収体。3. The broadband electromagnetic wave absorber for quasi-millimeter wave according to claim 1, wherein a powder filler inert to electromagnetic waves is added in an amount of 50% by volume or less in addition to the soft magnetic metal powder.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001400850A JP2003193103A (en) | 2001-12-28 | 2001-12-28 | Broad-band electromagnetic wave absorber for quasi- millimeter wave |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001400850A JP2003193103A (en) | 2001-12-28 | 2001-12-28 | Broad-band electromagnetic wave absorber for quasi- millimeter wave |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2003193103A true JP2003193103A (en) | 2003-07-09 |
Family
ID=27605201
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2001400850A Pending JP2003193103A (en) | 2001-12-28 | 2001-12-28 | Broad-band electromagnetic wave absorber for quasi- millimeter wave |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2003193103A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006059502A1 (en) * | 2004-11-30 | 2006-06-08 | Bridgestone Corporation | Rubber composition for wave absorber and wave absorbing sheet |
| US9450312B2 (en) | 2013-09-20 | 2016-09-20 | Kabushiki Kaisha Toshiba | Magnetic metal particle aggregate and radio wave absorber |
| KR102204744B1 (en) | 2019-10-16 | 2021-01-19 | 한국항공우주산업 주식회사 | Rubber matrix composites for impedance matching and application method thereof |
| WO2022210153A1 (en) * | 2021-03-31 | 2022-10-06 | 富士フイルム株式会社 | Structure, method for manufacturing structure, and composition |
-
2001
- 2001-12-28 JP JP2001400850A patent/JP2003193103A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006059502A1 (en) * | 2004-11-30 | 2006-06-08 | Bridgestone Corporation | Rubber composition for wave absorber and wave absorbing sheet |
| US9450312B2 (en) | 2013-09-20 | 2016-09-20 | Kabushiki Kaisha Toshiba | Magnetic metal particle aggregate and radio wave absorber |
| KR102204744B1 (en) | 2019-10-16 | 2021-01-19 | 한국항공우주산업 주식회사 | Rubber matrix composites for impedance matching and application method thereof |
| WO2022210153A1 (en) * | 2021-03-31 | 2022-10-06 | 富士フイルム株式会社 | Structure, method for manufacturing structure, and composition |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111136280A (en) | Flower-shaped Fe/Fe3C/Fe3O4Composite wave-absorbing material and preparation method thereof | |
| JP3599205B2 (en) | Inductor element for noise suppression | |
| KR101458839B1 (en) | Electric wave absorption sheet for near-field and manufacturing method thereof | |
| Alam et al. | Influence of multi-walled carbon nanotubes (MWCNTs) volume percentage on the magnetic and microwave absorbing properties of BaMg0. 5Co0. 5TiFe10O19/MWCNTs nanocomposites | |
| JP2009021403A (en) | Electromagnetic wave suppressing sheet | |
| EP2136613B1 (en) | Sheet for prevention of electromagnetic wave interference, flat cable for high-frequency signal, flexible print substrate, and method for production of sheet for prevention of electromagnetic wave interference | |
| Yanagimoto et al. | Effect of powder compositions on GHz microwave absorption of EM absorbing sheets | |
| JP2007180289A (en) | Electromagnetic wave absorber | |
| JP2003193103A (en) | Broad-band electromagnetic wave absorber for quasi- millimeter wave | |
| JP2010135567A (en) | Radio wave absorbing material | |
| US20070052575A1 (en) | Near-field electromagnetic wave absorber | |
| JP2003332113A (en) | Flat soft magnetic powder and composite magnetic sheet using the same | |
| US6850182B2 (en) | Electromagnetic wave absorber | |
| JPH11269503A (en) | Iron-base nano-crystal magnetic powder, its production, and radio wave noise inhibiting member using the same | |
| JP2000138492A (en) | Electromagnetic wave absorber | |
| JPH1027986A (en) | Radio wave absorber | |
| JP2003060383A (en) | Electromagnetic wave absorbing sheet | |
| JP2000232294A (en) | Electromagnetic wave absorber for high-frequency region | |
| JP2000228599A (en) | Electromagnetic wave absorber utilizing matching thickness and its manufacturing method | |
| JP2004140335A (en) | Electromagnetic wave absorbing material | |
| JP6588749B2 (en) | Insulation coating flat powder | |
| JP2002083704A (en) | Radio wave absorber | |
| JPH05299872A (en) | Wave absorber for 900mhz-band | |
| JP2004111394A (en) | Conductive sheet composition, and manufacturing method of conductive sheet | |
| KR102075979B1 (en) | Complex sheet having excellent abilities of electromagnetic shielding, thermal dissipation and electromagnetic waves absorbsortion, and method of manufacturing the same |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20041026 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20050525 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20050628 |
|
| A02 | Decision of refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A02 Effective date: 20051101 |