JPH0139240B2 - - Google Patents
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- Publication number
- JPH0139240B2 JPH0139240B2 JP55142045A JP14204580A JPH0139240B2 JP H0139240 B2 JPH0139240 B2 JP H0139240B2 JP 55142045 A JP55142045 A JP 55142045A JP 14204580 A JP14204580 A JP 14204580A JP H0139240 B2 JPH0139240 B2 JP H0139240B2
- Authority
- JP
- Japan
- Prior art keywords
- radio wave
- wave absorbing
- frequency
- carbon fiber
- dielectric constant
- 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.)
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- Aerials With Secondary Devices (AREA)
Description
【発明の詳細な説明】
（産業上の利用分野）
この発明は、船舶や航空機等の船体や機体に貼
り付けたり、橋梁やビル等の外壁に貼り付けて、
マイクロ波帯域の電波に対して使用する整合型電
波吸収材に関する。[Detailed Description of the Invention] (Industrial Application Field) This invention can be applied to the hull or body of a ship or aircraft, or to the outer wall of a bridge or building, etc.
This invention relates to a matching type radio wave absorbing material used for radio waves in the microwave band.
（従来の技術）
電波吸収材としては、従来、炭素繊維層の一面
に反射層を設けたものや、ゴムと炭素短繊維との
複合材料からなるものや、誘電体層の一面に炭素
繊維層を設けたもの等、いいろいろなものが知ら
れている。(Prior art) Conventional radio wave absorbing materials include those that have a reflective layer on one side of a carbon fiber layer, those that are made of a composite material of rubber and short carbon fibers, and those that have a carbon fiber layer on one side of a dielectric layer. There are various types of devices known, including those with .
しかしながら、これら従来の電波吸収材は、い
ずれも、吸収による反射減衰量が10dB程度と低
く、実用上採り得る厚みの限界である厚み10mm以
下の範囲で15dB以上の反射減衰量を示す帯域幅
が0.5GHz程度にすぎない。すなわち、電波吸収
効果が低い。 However, all of these conventional radio wave absorbing materials have a low return loss of about 10 dB due to absorption, and have a bandwidth that shows a return loss of 15 dB or more at a thickness of 10 mm or less, which is the limit of practical thickness. It is only about 0.5GHz. That is, the radio wave absorption effect is low.
（発明が解決しようとする課題）
この発明は、従来の電波吸収材の上述した問題
点に鑑み、薄くても、吸収による反射減衰量が
15dBを超える帯域幅を広くとれる整合型電波吸
収材を提供しようというものである。(Problems to be Solved by the Invention) In view of the above-mentioned problems of conventional radio wave absorbers, the present invention aims to reduce the amount of return loss due to absorption even if it is thin.
The aim is to provide a matched radio wave absorbing material that can provide a wide bandwidth exceeding 15 dB.
（課題を解決するための手段）
上記目的は、炭素繊維と樹脂との複合材料から
なる電波吸収層と、この電波吸収層の一面に設け
た、導電材料からなる電波反射層とを有し、か
つ、上記炭素繊維は、周波数10GHzにおける複素
比誘電率εcが、
εc＝（８〜12）−ｊ（３〜５）
の範囲にあることを特徴とする整合型電波吸収材
によつて達成される。(Means for solving the problem) The above object has a radio wave absorbing layer made of a composite material of carbon fiber and resin, and a radio wave reflecting layer made of a conductive material provided on one surface of the radio wave absorbing layer, And, the carbon fiber is a matched radio wave absorbing material characterized in that a complex dielectric constant ε c at a frequency of 10 GHz is in the range of ε c = (8 to 12) - j (3 to 5). achieved.
この発明の電波吸収材は、炭素繊維と樹脂との
複合材料からなる電波吸収層の一面に、導電材料
からなる電波反射層を設けてなる整合型電波吸収
材である。そうして、使用時には、電波吸収層が
電波の到来方向に向けられる。 The radio wave absorbing material of the present invention is a matched radio wave absorbing material in which a radio wave reflecting layer made of a conductive material is provided on one surface of a radio wave absorbing layer made of a composite material of carbon fiber and resin. Then, during use, the radio wave absorbing layer is oriented in the direction of arrival of radio waves.
この発明で用いる炭素繊維は、周波数10GHzに
おける複素比誘電率εcが、
εc＝（８〜12）−ｊ（３〜５）
の範囲にあるものでなければならない。周波数
10GHzにおける複素比誘電率εcが上記範囲にない
炭素繊維によつては、マイクロ波帯域における吸
収による反射減衰量が15dBを超える帯域幅を広
くとれる薄い電波吸収材を得ることができない。
すなわち、この発明の目的と達成することができ
ない。その理由は、厚みをいかに変えても、規格
化入力インピーダンスの整合をとれなくなるから
である。なお、炭素繊維の複素比誘電率εcは、製
造時の焼成温度や焼成時間等に依存する。換言す
れば、これらの製造条件を選定することで、複素
比誘電率εcが上記範囲にある炭素繊維を得ること
ができる。 The carbon fiber used in this invention must have a complex dielectric constant ε c at a frequency of 10 GHz in the range of ε c =(8 to 12)−j(3 to 5). frequency
With carbon fibers whose complex dielectric constant ε c at 10 GHz is not within the above range, it is impossible to obtain a thin radio wave absorbing material that can have a wide bandwidth in which the amount of return loss due to absorption in the microwave band exceeds 15 dB.
That is, the purpose of this invention cannot be achieved. The reason for this is that no matter how much the thickness is changed, the standardized input impedance cannot be matched. Note that the complex dielectric constant ε c of carbon fiber depends on the firing temperature, firing time, etc. during manufacturing. In other words, by selecting these manufacturing conditions, it is possible to obtain carbon fibers having a complex dielectric constant ε c within the above range.
上述した炭素繊維は、短繊維、マツト、長繊
維、織物等の形で、後述する樹脂中に30〜70体積
％程度含まれている。なかでも、炭素繊維同士の
電気的接触が良好で、高い電波吸収効果が得られ
る織物の形が最も好ましい。そうして、炭素繊維
は、可能な限り、電波吸収層の面と平行な方向に
向けるのが好ましい。 The above-mentioned carbon fibers are contained in the resin described below in the form of short fibers, mats, long fibers, textiles, etc. in an amount of about 30 to 70% by volume. Among these, the most preferred is a woven fabric that provides good electrical contact between carbon fibers and provides a high radio wave absorption effect. The carbon fibers are preferably oriented as parallel to the plane of the radio wave absorbing layer as possible.
電波吸収層は、上述した炭素繊維と、樹脂との
複合材料からなり、１〜５mm程度の厚みを有して
いるが、そのような電波吸収層の、いわゆる母材
となつている樹脂は、エポキシ樹脂、不飽和ポリ
エステル樹脂、ポリイミド樹脂等の熱硬化性樹脂
や、ポリアミド樹脂、塩化ビニル樹脂、ポリフエ
ニレンサルフアイド樹脂等の熱可塑性樹脂であ
る。なかでも、炭素繊維との接着性に優れ、しか
も、耐候性に優れているエポキシ樹脂が最も好ま
しい。 The radio wave absorbing layer is made of a composite material of the above-mentioned carbon fiber and resin, and has a thickness of about 1 to 5 mm, but the resin that is the so-called base material of such a radio wave absorbing layer is These include thermosetting resins such as epoxy resins, unsaturated polyester resins, and polyimide resins, and thermoplastic resins such as polyamide resins, vinyl chloride resins, and polyphenylene sulfide resins. Among these, epoxy resin is most preferred because it has excellent adhesion to carbon fibers and weather resistance.
樹脂には、同じ、たとえばエポキシ樹脂であつ
ても、いろいろな種類、性質のものがあるが、な
かでも、周波数10GHz、温度15℃における複素比
誘電率εcが、
εr＝（２〜４）−ｊ（５×10-3〜２×10-2）
の範囲にあるようなものが好ましい。そのような
範囲の複素比誘電率をもつ樹脂を使用すると、理
由は明らかでないが、上述した炭素繊維との組み
合せにおいて、吸収による反射減衰量が15dBを
超える帯域幅が広がり、また、その特性がより平
坦になる。 There are various types and properties of the same resin, such as epoxy resin, but among them, the complex dielectric constant ε c at a frequency of 10 GHz and a temperature of 15°C is ε r = (2 to 4 )-j (5×10 −3 to 2×10 −2 ) is preferable. If a resin with a complex dielectric constant in such a range is used, for reasons that are not clear, in combination with the above-mentioned carbon fiber, the bandwidth where the return loss due to absorption exceeds 15 dB will be expanded, and its characteristics will be improved. becomes flatter.
電波吸収層の一面の電波反射層は、電波吸収層
を透過してきた電波をその電波吸収層に向かつて
反射せしめるもので、アルムニウム、銅、銀等の
導電材料の板、シート、薄膜等で構成されてい
る。炭素繊維の織物等を用いることもできる。 The radio wave reflecting layer on one side of the radio wave absorbing layer reflects the radio waves that have passed through the radio wave absorbing layer toward the radio wave absorbing layer, and is made of a plate, sheet, thin film, etc. of a conductive material such as aluminum, copper, or silver. has been done. A carbon fiber fabric or the like may also be used.
この発明の電波吸収材は、その電波吸収層が上
記炭素繊維を含んでいることを必須とするが、そ
れ以外に、ガラス繊維、芳香族ポリアミド繊維、
セラミツクス繊維（たとえば、アルミナ繊維やジ
ルコニア繊維）、シリコンカーバイド繊維等が含
まれていてもよい。また、ボロンナイトライドや
アルミナ等のフイラーを含んでいてもよい。これ
らの繊維やフイラーを混入すると、全体としてみ
た、上述した複素比誘電率εcの制御が容易にな
る。 In the radio wave absorbing material of the present invention, the radio wave absorbing layer must contain the above-mentioned carbon fibers, but in addition, glass fibers, aromatic polyamide fibers,
Ceramic fibers (for example, alumina fibers and zirconia fibers), silicon carbide fibers, etc. may be included. Further, filler such as boron nitride or alumina may be included. When these fibers or fillers are mixed, the above-mentioned complex dielectric constant ε c can be easily controlled as a whole.
また、樹脂として発泡樹脂を用いると、より軽
量な電波吸収材を得ることができるようになる。 Further, when a foamed resin is used as the resin, a lighter radio wave absorbing material can be obtained.
（実施態様）
第１図において、整合型電波吸収材は、周波数
が10GHzにおける複素比誘電率εcが、
εc＝（８〜12）−ｊ（３〜５）
の範囲にある炭素繊維からなる織物２と、エポキ
シ樹脂３との複合材料からなる板状電波吸収層１
と、この電波吸収層１の一面に貼り付けて設け
た、アルミニウム板からなる電波反射層４とを有
している。この電波吸収材は、電波吸収層１の面
を電波Ｗの到来方向に向けて使用する。(Embodiment) In FIG. 1, the matched radio wave absorber is made of carbon fiber whose complex dielectric constant ε c at a frequency of 10 GHz is in the range of ε c = (8 to 12) - j (3 to 5). A plate-shaped radio wave absorbing layer 1 made of a composite material of a fabric 2 and an epoxy resin 3.
and a radio wave reflective layer 4 made of an aluminum plate and attached to one surface of the radio wave absorbing layer 1. This radio wave absorbing material is used with the surface of the radio wave absorbing layer 1 facing the direction in which the radio waves W arrive.
（実施例および比較例）
実施例 １
周波数10GHzにおける複素比誘電率が10−j4の
炭素繊維の織物を６枚重ね合わせ、これと、周波
数10GHz、温度15℃における複素比誘電率が３−
ｊ（１×10-2）のエポキシ樹脂との複合材料から
なり、目付が1680ｇ／m2で、厚みが2.41mmである
電波吸収層の一面に、厚みが１mmのアルミニウム
板からなる電波反射層を貼り付け、電波吸収材を
得た。(Examples and Comparative Examples) Example 1 Six carbon fiber fabrics with a complex dielectric constant of 10-j4 at a frequency of 10 GHz are stacked together, and this and a fabric with a complex dielectric constant of 3-j4 at a frequency of 10 GHz and a temperature of 15°C are stacked together.
A radio wave reflective layer made of an aluminum plate with a thickness of 1 mm is placed on one side of the radio wave absorbing layer, which is made of a composite material with epoxy resin of J (1 × 10 -2 ) and has a basis weight of 1680 g/m 2 and a thickness of 2.41 mm. was attached to obtain a radio wave absorbing material.
この電波吸収材について、周波数と、吸収によ
反射減衰量との関係を調べたところ、第２図に示
すように、周波数が9.4〜10.8GHzの間において
15dB以上の反射減衰量が得られた、なお、第２
図において、横軸のＦは周波数（ＧHz）であり、
縦軸のＬは反射減衰量（dB）である。 When we investigated the relationship between frequency and return loss due to absorption for this radio wave absorbing material, we found that when the frequency is between 9.4 and 10.8 GHz, as shown in Figure 2,
A return loss of 15 dB or more was obtained.
In the figure, F on the horizontal axis is the frequency (GHz),
L on the vertical axis is return loss (dB).
実施例 ２
周波数10GHzにおける複素比誘電率が８−j3.6
の炭素繊維の織物を６枚重ね合わせ、これと、周
波数10GHz、温度15℃における複素比誘電率が３
−ｊ（１×10-2）のエポキシ樹脂との複合材料か
らなり、目付が1890ｇ／m2で、厚みが2.7mmであ
る電波吸収層の一面に、厚みが１mmのアルミニウ
ム板からなる電波反射層を貼り付け、電波吸収材
を得た。Example 2 Complex dielectric constant at frequency 10GHz is 8-j3.6
Six carbon fiber fabrics are stacked together, and the complex dielectric constant is 3 at a frequency of 10 GHz and a temperature of 15°C.
-j (1 x 10 -2 ) of composite material with epoxy resin, has a basis weight of 1890 g/m 2 and is 2.7 mm thick. On one side of the radio wave absorbing layer is a radio wave reflecting layer made of a 1 mm thick aluminum plate. The layers were attached to obtain a radio wave absorbing material.
この電波吸収材について、実施例１と同様の試
験をしたところ、第３図に示すように、周波数が
9.3〜10.9GHzの間において15dB以上の反射減衰
量が得られた。 When this radio wave absorbing material was subjected to the same test as in Example 1, as shown in Figure 3, the frequency was
A return loss of more than 15 dB was obtained between 9.3 and 10.9 GHz.
実施例 ３
周波数10GHzにおける複素比誘電率が12−j4.3
の炭素繊維の織物を６枚重ね合わせ、これと、周
波数10GHz、温度15℃における複素比誘電率が３
−ｊ（１×10-2）のエポキシ樹脂との複合材料か
らなり、目付が1540ｇ／m2で、厚みが2.2mmであ
る電波吸収層の一面に、厚みが１mmのアルミニウ
ム板からなる電波反射層を貼り付け、電波吸収材
を得た。Example 3 Complex dielectric constant at frequency 10GHz is 12−j4.3
6 carbon fiber fabrics are stacked together, and the complex dielectric constant is 3 at a frequency of 10 GHz and a temperature of 15°C.
A radio wave absorbing layer made of a composite material with an epoxy resin of -j (1×10 -2 ), has a basis weight of 1540 g/m 2 and a thickness of 2.2 mm, is covered with a radio wave reflecting layer made of an aluminum plate with a thickness of 1 mm. The layers were attached to obtain a radio wave absorbing material.
この電波吸収材について、実施例１と同様の試
験をしたところ、第４図に示すように、周波数が
9.3〜10.7GHzの間において15dB以上の反射減衰
量が得られた。 When this radio wave absorbing material was subjected to the same test as in Example 1, the frequency was found to be as shown in Figure 4.
A return loss of more than 15 dB was obtained between 9.3 and 10.7 GHz.
比較例 １
周波数10GHzにおける複素比誘電率が６−j1.4
の炭素繊維の織物を６枚重ね合わせ、これと、周
波数10GHz、温度15℃における複素比誘電率が３
−ｊ（１×10-2）のエポキシ樹脂との複合材料か
らなり、目付が2310ｇ／m2で、厚みが3.3mmであ
る電波吸収層の一面に、厚みが１mmのアルミニウ
ム板からなる電波反射層を貼り付け、電波吸収材
を得た。Comparative example 1 Complex dielectric constant at frequency 10GHz is 6-j1.4
Six carbon fiber fabrics are stacked together, and the complex dielectric constant is 3 at a frequency of 10 GHz and a temperature of 15°C.
-j (1×10 -2 ) composite material with epoxy resin, has a basis weight of 2310 g/m 2 , and is 3.3 mm thick. On one side of the radio wave absorbing layer is a radio wave reflecting layer made of an aluminum plate with a thickness of 1 mm. The layers were attached to obtain a radio wave absorbing material.
この電波吸収材について、実施例１と同様の試
験をしたところ、第５図に示すように、15dB以
上の反射減衰量は得られなかつた。この特性は、
厚みを１mmから50mmまで変えても、同様であつ
た。 When this radio wave absorbing material was subjected to the same test as in Example 1, as shown in FIG. 5, no return loss of 15 dB or more was obtained. This characteristic is
The same result was obtained even when the thickness was changed from 1 mm to 50 mm.
比較例 ２
周波数10GHzにおける複素比誘電率が11−j6の
炭素繊維の織物を６枚重ね合わせ、これと、周波
数10GHz、温度15℃における複素比誘電率が３−
ｊ（１×10-2）のエポキシ樹脂との複合材料から
なり、目付が1610ｇ／m2で、厚みが2.3mmである
電波吸収層の一面に、厚みが１mmのアルミニウム
板からなる電波反射層を貼り付け、電波吸収材を
得た。Comparative Example 2 Six sheets of carbon fiber fabric with a complex dielectric constant of 11-j6 at a frequency of 10 GHz and a complex dielectric constant of 3-j6 at a frequency of 10 GHz and a temperature of 15°C are stacked together.
A radio wave reflecting layer made of an aluminum plate with a thickness of 1 mm is placed on one side of the radio wave absorbing layer, which is made of a composite material with epoxy resin of J (1 × 10 -2 ) and has a basis weight of 1610 g/m 2 and a thickness of 2.3 mm. was attached to obtain a radio wave absorbing material.
この電波吸収材について、実施例１と同様の試
験をしたところ、第６図に示すように、15dB以
上の反射減衰量が得られるのは、わずかに9.9〜
10GHzの範囲のみであつた。 When this radio wave absorbing material was tested in the same manner as in Example 1, as shown in Figure 6, only 9.9 to
It was only in the 10GHz range.
（発明の効果）
この発明の整合型電波吸収材は、炭素繊維と樹
脂との複合材料からなる電波吸収層と、この電波
吸収層の一面に設けた、導電材料からなる電波反
射層とを有し、かつ、炭素繊維は、周波数10GHz
における複素比誘電率εcが、
εc＝（８〜12）−ｊ（３〜５）
の範囲にあるものであるから、実施例にも示した
ように、薄くても、吸収による反射減衰量が
15dBを超える帯域幅を大変広くとることができ
るようになる。(Effects of the Invention) The matched radio wave absorbing material of the present invention has a radio wave absorbing layer made of a composite material of carbon fiber and resin, and a radio wave reflecting layer made of a conductive material provided on one surface of this radio wave absorbing layer. And carbon fiber has a frequency of 10GHz
Since the complex dielectric constant ε c is in the range of ε c = (8 to 12) - j (3 to 5), even if it is thin, reflection attenuation due to absorption will occur as shown in the example. The amount
It becomes possible to obtain a very wide bandwidth exceeding 15 dB.
第１図は、この発明の一実施態様に係る整合型
電波吸収材の概略側面図、第２図〜第６図は、実
施例および比較例に係る整合型電波吸収材の、周
波数と反射減衰量との関係を示すグラフである。
１：電波吸収層、２：炭素繊維織物、３：エポ
キシ樹脂、４：電波反射層、Ｗ：電波。
FIG. 1 is a schematic side view of a matched radio wave absorber according to an embodiment of the present invention, and FIGS. 2 to 6 show frequencies and reflection attenuation of matched radio wave absorbers according to an example and a comparative example. It is a graph showing the relationship with quantity. 1: Radio wave absorption layer, 2: Carbon fiber fabric, 3: Epoxy resin, 4: Radio wave reflection layer, W: Radio wave.
Claims (1)
収層と、この電波吸収層の一面に設けた、導電材
料からなる電波反射層とを有し、かつ、上記炭素
繊維は、周波数10GHzにおける複素比誘電率εc
が、 εc＝（８〜12）−ｊ（３〜５） の範囲にあることを特徴とする整合型電波吸収
材。[Claims] 1. A radio wave absorbing layer made of a composite material of carbon fiber and resin, and a radio wave reflecting layer made of a conductive material provided on one surface of the radio wave absorbing layer, and the carbon fiber is , complex dielectric constant ε c at frequency 10 GHz
is in the range of ε c =(8-12)-j(3-5).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14204580A JPS5766699A (en) | 1980-10-13 | 1980-10-13 | Radiowave absorbing material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14204580A JPS5766699A (en) | 1980-10-13 | 1980-10-13 | Radiowave absorbing material |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5766699A JPS5766699A (en) | 1982-04-22 |
| JPH0139240B2 true JPH0139240B2 (en) | 1989-08-18 |
Family
ID=15306104
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14204580A Granted JPS5766699A (en) | 1980-10-13 | 1980-10-13 | Radiowave absorbing material |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5766699A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1992022193A1 (en) * | 1991-05-28 | 1992-12-10 | Osaka Gas Company Limited | Method for absorbing electromagnetic wave |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61207098U (en) * | 1985-06-18 | 1986-12-27 | ||
| JPS61207099U (en) * | 1985-06-18 | 1986-12-27 | ||
| JPS6214799U (en) * | 1985-07-10 | 1987-01-29 |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS53110402A (en) * | 1977-03-09 | 1978-09-27 | Tokyo Keiki Kk | Radio absorbing plate |
| JPS5418382A (en) * | 1977-07-11 | 1979-02-10 | Toma Kohan Kk | Assembled container |
| JPS55120199A (en) * | 1979-03-09 | 1980-09-16 | Mitsuo Wachi | Thin layer sealing unit internally mounting electromagnetic microwave reflection restricting material |
-
1980
- 1980-10-13 JP JP14204580A patent/JPS5766699A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1992022193A1 (en) * | 1991-05-28 | 1992-12-10 | Osaka Gas Company Limited | Method for absorbing electromagnetic wave |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5766699A (en) | 1982-04-22 |
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