JP4602429B2 - Radio wave absorber - Google Patents

Radio wave absorber Download PDF

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JP4602429B2
JP4602429B2 JP2008042146A JP2008042146A JP4602429B2 JP 4602429 B2 JP4602429 B2 JP 4602429B2 JP 2008042146 A JP2008042146 A JP 2008042146A JP 2008042146 A JP2008042146 A JP 2008042146A JP 4602429 B2 JP4602429 B2 JP 4602429B2
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pyramid
radio wave
wave absorber
molded body
side wall
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賢一 畠山
龍哉 中村
美佳 廣瀬
暁 葭内
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Hyogo Prefectural Government
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本発明は電磁波の反射を抑制する電波吸収体に関するものである。   The present invention relates to a radio wave absorber that suppresses reflection of electromagnetic waves.

電磁波の不要な反射を無くする電波吸収体は、実用化されており、電波吸収体の素材や構造は幾つか知られている。電波吸収体は、到来する電磁波エネルギーを吸収して熱に変換するデバイスであり、カーボンまたは金属粉等の導電材を樹脂に混合した損失材や、フェライト等の磁性材を利用した損失材などが電波吸収体の素材として用いられている。これらの損失材を用いて単層形、２層形、ピラミッド形等各種の構造により電波吸収体が設計されている。特に高吸収性能が必要な場合および広周波数帯域で使用する場合には、ピラミッド形電波吸収体が用いられる。ピラミッド形電波吸収体としては、発泡材を母材として用い、該発泡材の空孔部にカーボン等の導電材を充填した損失材をピラミッド形に成形したピラミッド形電波吸収体、あるいは中空のピラミッド構造にして、該ピラミッド形状表面部にのみ導電膜を施したピラミッド形電波吸収体が知られている（非特許文献１参照）。   Radio wave absorbers that eliminate unnecessary reflection of electromagnetic waves have been put into practical use, and several materials and structures of radio wave absorbers are known. A radio wave absorber is a device that absorbs incoming electromagnetic wave energy and converts it into heat, such as a loss material in which a conductive material such as carbon or metal powder is mixed with a resin, or a loss material that uses a magnetic material such as ferrite. Used as a material for radio wave absorbers. Using these lossy materials, radio wave absorbers are designed with various structures such as a single layer type, a two layer type, and a pyramid type. In particular, when high absorption performance is required and when used in a wide frequency band, a pyramidal electromagnetic wave absorber is used. As the pyramid-shaped wave absorber, a pyramid-shaped wave absorber formed by using a foam material as a base material, and forming a lossy material in which pores of the foam material are filled with a conductive material such as carbon into a pyramid shape, or a hollow pyramid A pyramidal electromagnetic wave absorber having a structure in which a conductive film is applied only to the surface portion of the pyramid shape is known (see Non-Patent Document 1).

清水康敬、杉浦行、石野健編集、「電磁波の吸収と遮蔽」日経技術図書株式会社、１９９９年９月１０日発行、Ｐ．１８７Yasutaka Shimizu, Yuki Sugiura, Takeshi Ishino, “Absorption and Shielding of Electromagnetic Waves”, Nikkei Technical Books Co., Ltd., published on September 10, 1999, p. 187

近年、携帯電話や無線ＬＡＮの普及に伴い、周波数の近接した電磁波が空間に混在している。高品質な通信状態を達成するために、多くの電子機器では不要な電磁波の発生を抑制し、かつ外来電磁波に対して影響を受けにくくする対策が施されている。電子機器が発生する不要電磁波の放射強度評価や到来電磁波による誤動作評価、あるいは携帯電話やレーダなどの電磁波を放射する機器にあっては電磁波放射特性の評価等は通常、電波吸収体で内壁面を覆った電波暗室内で行われる。また、電磁波を放射する機器の周辺では周囲物体による反射・散乱波が不要電磁波となり、これを抑制する目的で該周囲物体に電波吸収体を施工する対策がとられている。   In recent years, with the spread of mobile phones and wireless LANs, electromagnetic waves with close frequencies are mixed in space. In order to achieve a high-quality communication state, many electronic devices take measures to suppress generation of unnecessary electromagnetic waves and make them less susceptible to external electromagnetic waves. For the evaluation of radiation intensity of unwanted electromagnetic waves generated by electronic equipment, malfunction evaluation due to incoming electromagnetic waves, or evaluation of electromagnetic radiation characteristics for equipment that radiates electromagnetic waves, such as mobile phones and radars, the inner wall surface is usually covered with a radio wave absorber. It takes place in a covered anechoic chamber. Further, in the vicinity of a device that radiates electromagnetic waves, reflected / scattered waves from surrounding objects become unnecessary electromagnetic waves, and measures are taken to construct a radio wave absorber on the surrounding objects in order to suppress this.

電波暗室用の電波吸収体は広周波数帯域が要求されるので、その内壁面にはピラミッド形吸収体が装着される。大電力の電磁波を放射するレーダの放射特性評価用、あるいは大電力の電磁波を電子機器に照射して誤動作状況を評価するイミュニティ評価用の電波暗室では、内壁面に装着する電波吸収体には耐電力特性が要求される。ピラミッド形吸収体の母材として、従来、多用されている発泡材は、熱に弱く大電力を吸収して発熱すると変形、変質して電波吸収性能が劣化することや、発火する危険性がある。そのため、耐電力特性に優れるピラミッド形電波吸収体が望まれている。   Since a radio wave absorber for an anechoic chamber requires a wide frequency band, a pyramidal absorber is attached to the inner wall surface thereof. In an anechoic chamber for evaluating the radiation characteristics of a radar that emits high-power electromagnetic waves, or for evaluating immunity by irradiating electronic equipment with high-power electromagnetic waves to evaluate malfunctions, the electromagnetic wave absorber attached to the inner wall surface is not resistant. Power characteristics are required. As a base material for pyramid-shaped absorbers, foam materials that have been widely used in the past are susceptible to heat and absorb high power to generate heat. . Therefore, a pyramid type electromagnetic wave absorber excellent in power durability is desired.

さらに、電波吸収体の母材となる樹脂や発泡材は耐候性が十分ではなく、電波吸収体の屋外使用では長期に亘る使用に限界があった。そのため材質の劣化を軽減するために、電波吸収体表面に耐候性塗膜を施すなどの対策がとられているが十分ではない。屋外用電波吸収体は施工箇所によっては修理や取り替えの必要がない恒久的使用が望まれる場合もあり、耐候性に優れる電波吸収体が望まれている。   Further, the resin and foam material used as the base material of the radio wave absorber have insufficient weather resistance, and the radio wave absorber has a limit in long-term use when used outdoors. Therefore, in order to reduce the deterioration of the material, measures such as applying a weather-resistant coating film on the surface of the radio wave absorber are taken, but it is not sufficient. The outdoor wave absorber may be required to be used permanently without requiring repair or replacement depending on the construction site, and a wave absorber excellent in weather resistance is desired.

上記課題を解決するために、図１に示すような、粘土素地からなるピラミッド成形体の表面に、いぶし瓦製造法によりカーボン層を形成し、ピラミッド形の電波吸収体を構成する。   In order to solve the above-mentioned problems, a carbon layer is formed on the surface of a pyramid molded body made of a clay base as shown in FIG.

いぶし瓦製造法とは伝統的な瓦焼成法の一種であり、粘土素地を成形・乾燥した後、焼成炉内に入れ、約１０００℃に粘土素地を加熱焼成した後、炉内を密閉し、外気と遮断した状態で、炭化水素に富むガスを導入することで、燻化処理を行う製造方法である。燻化処理とは、焼成過程において炭化水素ガスに含まれる炭素が、粘土素地表面で熱分解して、膜状の炭素が粘土素地表面に沈着、及びグラファイト結晶を層状に構成し、厚み数ミクロンメートル程度のカーボン層を形成するものである。このカーボン層は、いぶし瓦に灰色の独特な風合いを与えると共に、瓦の吸水性を低減させる効果や耐候性を高める効果をもつ。   Ibushi tile manufacturing method is a kind of traditional tile firing method. After molding and drying the clay body, put it in a firing furnace, heat and fire the clay body to about 1000 ° C, then seal the interior of the furnace, This is a manufacturing method in which a hatching process is performed by introducing a gas rich in hydrocarbons in a state of being blocked from outside air. In the hatching process, the carbon contained in the hydrocarbon gas is pyrolyzed on the surface of the clay base during the firing process, the film-like carbon is deposited on the surface of the clay base, and the graphite crystals are layered to form a thickness of several microns. A carbon layer of about a meter is formed. This carbon layer gives the smoldering tile a unique gray texture, and also has the effect of reducing the water absorption of the tile and the weather resistance.

瓦表面に形成されるカーボン層は電気的に見れば導電膜である。粘土素地で作製した棒状試料をいぶし瓦製造法にて焼結し、該棒状試料の表面に、いぶし瓦と同様にカーボン層を形成して導電膜の面抵抗を４端子法で測定したところ、面抵抗は７１［Ω］であった。   The carbon layer formed on the roof surface is a conductive film when viewed electrically. When the rod-shaped sample prepared from the clay base was sintered by the smoldering tile manufacturing method, a carbon layer was formed on the surface of the rod-shaped sample in the same manner as the smoldering tile, and the sheet resistance of the conductive film was measured by the four-terminal method. The sheet resistance was 71 [Ω].

前記の中空ピラミッド形電波吸収体において、該ピラミッド形状表面部にのみ導電膜を形成する場合の、該導電膜の面抵抗は数１０［Ω］〜百数１０［Ω］である。このことと、いぶし瓦製造法により得られるカーボン層の面抵抗より、発明者らは、粘土素地を用いて図１に示すようなピラミッド成形体を作製し、該ピラミッド成形体の表面にいぶし瓦製造法によりカーボン膜を形成すれば、ピラミッド形の電波吸収体が構成できるとの着想を得た。   In the hollow pyramid-shaped electromagnetic wave absorber, when a conductive film is formed only on the surface portion of the pyramid shape, the surface resistance of the conductive film is several tens [Ω] to hundreds [10] [Ω]. Based on this and the surface resistance of the carbon layer obtained by the method of manufacturing the smoldering tile, the inventors made a pyramid molded body as shown in FIG. The idea was that if a carbon film was formed by the manufacturing method, a pyramidal wave absorber could be constructed.

高出力レーダの放射電力ピーク値は数ＭＷに達するが、間欠的に電磁波を放射するパルスレーダにおける平均放射電力はこの数１００分の１程度になり、仮に平均放射電力を１００ｍ２の電波吸収体で受けるとすると、電波吸収体に入射する電力密度は数１００Ｗ／ｍ２である。電波吸収体は大電力電磁波を吸収すると電磁波エネルギーが熱に変換されて温度が上昇し、放熱とのバランスで温度はある一定値に収束する。電力密度が数１００Ｗ／ｍ２のマイクロ波を吸収するときの電波吸収体の温度上昇は経験上最大でも３００℃〜４００℃である。一方、いぶし瓦製造法においては前記のように１０００℃程度で焼成するので、いぶし瓦製造法で製作したピラミッド形の電波吸収体は、電力密度が数１００Ｗ／ｍ２程度のマイクロ波吸収では材質の変形、変質は生じず、耐電力特性に優れるという特徴がある。 The peak value of radiated power of a high-power radar reaches several MW, but the average radiated power in a pulse radar that radiates electromagnetic waves intermittently is about 1/100 of this, and the radio wave absorber is assumed to have an average radiated power of 100 m 2. , The power density incident on the radio wave absorber is several hundred W / m 2 . When a radio wave absorber absorbs high-power electromagnetic waves, the electromagnetic energy is converted into heat and the temperature rises, and the temperature converges to a certain value in balance with heat dissipation. The temperature rise of the radio wave absorber when absorbing a microwave having a power density of several hundred W / m 2 is 300 ° C. to 400 ° C. at the maximum based on experience. On the other hand, in the method of manufacturing the smoldering tile, it is fired at about 1000 ° C. as described above. Therefore, the pyramidal wave absorber manufactured by the method of manufacturing the smoldering tile is made of a material that absorbs microwaves with a power density of about several hundred W / m 2. No deformation or alteration occurs, and it has the characteristics of excellent power durability.

また、いぶし瓦製造法で作製したピラミッド形の電波吸収体は、形状以外は素地、製造法ともにいぶし瓦と実質的に同様であるから、いぶし瓦と同等に長期屋外使用に耐え、耐候性に非常に優れるという特徴がある。   In addition, the pyramid-shaped wave absorber manufactured by the Ibushi tile manufacturing method is substantially the same as the Ibushi tile except for the shape and the manufacturing method, so it can withstand long-term outdoor use as well as weather resistance. It is characterized by being very good.

粘土素地で作製されたピラミッド成形体の表面に、いぶし瓦製造法により形成されたカーボン膜は、入射波に対して中空のピラミッド構造表面部の導電膜と実質的に同じ作用をし、入射電磁波を吸収する。   The carbon film formed on the surface of the pyramid molded body made of a clay base by the method of manufacturing the smoldering tile acts on the incident wave substantially the same as the conductive film on the surface of the hollow pyramid structure. Absorbs.

本発明による電波吸収体は、従来、ピラミッド形電波吸収体として多く用いられている発泡材に比べて、熱に強く、大電力を吸収しても、電波吸収性能が劣化することなく、発火の危険性もない。さらに、耐候性に優れる点からも、短期間での取り替えなどメンテナンスの心配もなく、安全に電波吸収体を使用できるため、用途を広めることができる。   The radio wave absorber according to the present invention is more resistant to heat than the foamed material that is conventionally used as a pyramidal radio wave absorber, and even if it absorbs a large amount of power, the radio wave absorption performance does not deteriorate, There is no danger. Furthermore, from the point of being excellent in weather resistance, there is no worry of maintenance such as replacement in a short period of time, and the radio wave absorber can be used safely, so that the application can be widened.

図１は、電波吸収体の参考例を示す斜視図である。図１において、ピラミッド成形体１は、正方形底面の一辺の長さをｄ、高さをｐとするピラミッド形である。ｐとｄの比（ｐ／ｄ）は、従来の発泡材を母材とする中空ピラミッド吸収体の経験より勘案して、ｐ／ｄ＝１．２〜３．０としている。また、ピラミッド成形体１の表面（底面を除く）には、厚み数ミクロンメートル程度のカーボン層を形成する。 FIG. 1 is a perspective view showing a reference example of a radio wave absorber . In FIG. 1, the pyramid molded body 1 has a pyramid shape in which the length of one side of a square bottom is d and the height is p. The ratio of p and d (p / d) is set to p / d = 1.2 to 3.0 in consideration of the experience of a hollow pyramid absorber using a conventional foamed material as a base material. In addition, a carbon layer having a thickness of about several micrometers is formed on the surface (excluding the bottom surface) of the pyramid molded body 1.

図２は、図１のＡ−Ａ線断面図（ピラミッド内部を粘土素地で充填形成した構造）である。図３は、図１のＡ−Ａ線断面図であり、（ａ）はピラミッド内部を空洞にした構造を示したもので、（ｂ）は（ａ）のＤ−Ｄ線拡大断面図である。ピラミッド成形体１は、図２に示すようにピラミッド成形体１の全容積を粘土素地で充填形成した構造とするか、図ｒ３に示すように粘土素地を用いて厚みｔを有する側壁３で形成されたピラミッドを作製し、内部を空洞にした構造としてもよい。内部を空洞しにした構造の場合、ピラミッド成形体１の側壁３の厚みｔが薄いとピラミッド成形体１の機械的強度が弱くなるので、側壁３の厚さｔは１０ｍｍ〜２０ｍｍの範囲が望ましい。焼成炉内において炭化水素ガスはピラミッド成形体１内部の空洞にも入り込み、側壁内面でも熱分解しカーボン層２を形成する。したがって、図３に示す構造ではカーボン層２はピラミッド成形体１の側壁外面である面Ａだけでなく、空洞側にある側壁内面の面Ｂにも形成される。ピラミッド成形体１内部を空洞にすることで重量低減になると同時に、ピラミッド成形体１のカーボン層２を側壁３の内外面に存在させることになり、電磁波の吸収効果を高めることができる。   2 is a cross-sectional view taken along the line AA of FIG. 1 (a structure in which a pyramid is filled with a clay base). 3 is a cross-sectional view taken along the line AA of FIG. 1. FIG. 3A shows a structure in which the inside of the pyramid is hollow, and FIG. 3B is an enlarged cross-sectional view taken along the line DD of FIG. . The pyramid molded body 1 has a structure in which the entire volume of the pyramid molded body 1 is filled with a clay base as shown in FIG. 2, or is formed with a side wall 3 having a thickness t using a clay base as shown in FIG. It is also possible to produce a pyramid that has a hollow interior. In the case of a structure in which the inside is hollow, if the thickness t of the side wall 3 of the pyramid molded body 1 is thin, the mechanical strength of the pyramid molded body 1 becomes weak. Therefore, the thickness t of the side wall 3 is preferably in the range of 10 mm to 20 mm. . In the firing furnace, the hydrocarbon gas also enters the cavity inside the pyramid molded body 1 and thermally decomposes on the inner surface of the side wall to form the carbon layer 2. Therefore, in the structure shown in FIG. 3, the carbon layer 2 is formed not only on the surface A which is the outer surface of the side wall of the pyramid molded body 1 but also on the surface B of the inner surface of the side wall on the cavity side. By making the inside of the pyramid molded body 1 hollow, the weight is reduced, and at the same time, the carbon layer 2 of the pyramid molded body 1 is present on the inner and outer surfaces of the side wall 3, so that the electromagnetic wave absorption effect can be enhanced.

図４は、電波吸収体の他の参考例を示す斜視図である。電波吸収体は金属板上に並べて使用されるので、ピラミッド成形体１０の底面は金属板に当接する。電磁波がピラミッド先端から垂直に入射するとき電界成分は金属板に対して平行であり、電界成分は金属板上では境界条件より０である。したがって、ピラミッド成形体１０表面のカーボン層２のうち、底面に近い部分は電界成分が弱いので該カーボン層２を流れる電流が小さく、電波吸収効果に殆ど寄与しない。そこで、ピラミッド成形体１０の側壁に形成されたカーボン層２全体が電波吸収に寄与するようにするため、図４に示すように、ピラミッド成形体１０の下部に、該ピラミッド成形体１０の底面と同じ形状の四角形断面（四角形断面には、正方形、長方形、菱形を含む）を有する台座部４を一体化して設ける構造とする。 FIG. 4 is a perspective view showing another reference example of the radio wave absorber . Since the radio wave absorbers are used side by side on the metal plate, the bottom surface of the pyramid molded body 10 comes into contact with the metal plate. When electromagnetic waves enter perpendicularly from the tip of the pyramid, the electric field component is parallel to the metal plate, and the electric field component is zero on the metal plate due to boundary conditions. Therefore, in the carbon layer 2 on the surface of the pyramid molded body 10, the portion close to the bottom has a weak electric field component, so that the current flowing through the carbon layer 2 is small and hardly contributes to the radio wave absorption effect. Therefore, in order for the entire carbon layer 2 formed on the side wall of the pyramid molded body 10 to contribute to radio wave absorption, as shown in FIG. 4, the bottom surface of the pyramid molded body 10 and The base part 4 having a square section having the same shape (the square section includes a square, a rectangle, and a rhombus) is integrally provided.

電界成分は金属板から波長／４だけ離れた位置で最大であることと、ピラミッド形の電波吸収体はその高さが波長程度以上になる周波数で有効な吸収特性を示すことが知られているので、この両者を勘案して、台座の高さｑとピラミッドの高さｐの比を見積もると、ｑ／ｐ＝０．２５〜２．００の範囲であることが望ましい。   It is known that the electric field component is maximum at a position away from the metal plate by a wavelength of / 4, and that the pyramidal wave absorber exhibits effective absorption characteristics at a frequency where the height is about the wavelength or more. Therefore, in consideration of both, when the ratio between the height q of the pedestal and the height p of the pyramid is estimated, it is desirable that q / p = 0.25 to 2.00.

図５は、図４のＢ−Ｂ線断面図（ピラミッド内部を粘土素地で充填形成した構造）である。図６は、図４のＢ−Ｂ線断面図であり、（ａ）はピラミッド内部を空洞にした構造を示したもので、（ｂ）は（ａ）のＥ−Ｅ線拡大断面図である。台座部４を付加したピラミッド成形体１０においても、図５に示すようにピラミッド全容積を粘土素地で充填形成する構造や、図６に示すように粘土素地を用いて厚みｔを有する側壁３で形成されたピラミッドを作製し、内部を空洞にした構造にすることが可能である。   FIG. 5 is a cross-sectional view taken along the line BB in FIG. 4 (a structure in which the inside of the pyramid is filled with a clay base). 6 is a cross-sectional view taken along the line B-B in FIG. 4, (a) shows a structure in which the inside of the pyramid is hollow, and (b) is an enlarged cross-sectional view taken along the line EE of (a). . Also in the pyramid molded body 10 to which the pedestal portion 4 is added, a structure in which the entire pyramid volume is filled with a clay base as shown in FIG. 5 or a side wall 3 having a thickness t using a clay base as shown in FIG. It is possible to produce the formed pyramid and make the inside hollow.

図７は、本発明の一実施形態の電波吸収体を示す斜視図であり、（ａ）は全体斜視図、（ｂ）は放熱孔部分の拡大断面図である。図７において、内部が空洞のピラミッド成形体を、いぶし瓦製造法で焼成すると、図３および図６に示すようにピラミッド成形体１，１０の側壁外面である面Ａだけでなく、空洞側の側壁内面の面Ｂにもカーボン層２が形成される。したがって空洞側の側壁内面においても電磁波の吸収により発熱する。そこで、側壁内面の面Ｂにおける発熱を外部に放散するために、図７に示すようにピラミッド成形体１１の側壁３に、側壁内面から側壁外面に貫通する放熱孔５を複数個設ける。入射電磁波はピラミッド底面よりもピラミッド先端に近い領域で多く吸収される傾向があるので、前記放熱孔５はピラミッド先端に近い領域に多く設けるのが有効である。 7A and 7B are perspective views showing a radio wave absorber according to an embodiment of the present invention, wherein FIG. 7A is an overall perspective view, and FIG. 7B is an enlarged cross-sectional view of a heat radiation hole portion. In FIG. 7, when the pyramid molded body having a hollow inside is fired by the method of manufacturing a smoldering tile, not only the surface A which is the outer surface of the side wall of the pyramid molded body 1, 10 as shown in FIGS. The carbon layer 2 is also formed on the surface B of the side wall inner surface. Accordingly, heat is also generated by absorption of electromagnetic waves on the inner surface of the side wall on the cavity side. Therefore, in order to dissipate heat generated on the surface B on the inner surface of the side wall to the outside, a plurality of heat radiation holes 5 penetrating from the inner surface of the side wall to the outer surface of the side wall are provided in the side wall 3 of the pyramid molded body 11 as shown in FIG. Since incident electromagnetic waves tend to be absorbed more in the region near the pyramid tip than in the bottom of the pyramid, it is effective to provide more heat radiation holes 5 in the region near the pyramid tip.

図８は、電波吸収体の他の参考例を示す斜視図である。電波吸収体を使用する際には、複数個の電波吸収体の所定面（ピラミッド成形体の底面または台座部の底面）を整列させて隙間なく覆う。このとき複数個のピラミッド成形体を一体化して成形したものを用いると、取り扱いが便利であり、作業効率が向上する。図８は、図４に示すピラミッド成形体１０の６個を一体化成形したピラミッド成形体１２を示したものである。なお、一体化成形する個数は６個に限定されるものではなく、設置場所や環境に応じて適宜増減することが可能なものである。 FIG. 8 is a perspective view showing another reference example of the radio wave absorber . When using the radio wave absorber covers without gaps align the predetermined surface of the plurality of radio wave absorber (the bottom surface of the bottom or base of the pyramid shaped body). At this time, if a product obtained by integrating a plurality of pyramid molded bodies is used, handling is convenient and work efficiency is improved. FIG. 8 shows a pyramid molded body 12 in which six of the pyramid molded bodies 10 shown in FIG. 4 are integrally molded. Note that the number of integral moldings is not limited to six, and can be appropriately increased or decreased depending on the installation location and environment.

電波吸収体を実際に使用する場合、水平面に配列するだけでなく、垂直壁面にも配列する。垂直壁面に電波吸収体を配列する場合には、各電波吸収体を接着剤等で固定する方法が考えられるが、安全面を考慮すると取付金具で物理的に固定することが望ましい。 When the radio wave absorber is actually used, it is arranged not only on the horizontal plane but also on the vertical wall surface. When arranging radio wave absorbers on a vertical wall surface, a method of fixing each radio wave absorber with an adhesive or the like can be considered. However, in consideration of safety, it is desirable to physically fix the wave absorbers with a mounting bracket.

図９は、電波吸収体の他の参考例を示す斜視図であり、図１０は、図９の電波吸収体を切欠部の側から見た斜視図である。図９および図１０に示すように、ピラミッド成形体１３の台座部４の任意の一辺の中央部に突起部６を設け、かつ、該突起部６と対向する位置の辺の中央部に、隣に配置する他のピラミッド成形体１３の突起部６を挿入するための切欠部８を設ける構造にする。また、前記突起部６には取付金具９を挿通するための、通し孔７を設ける。 FIG. 9 is a perspective view showing another reference example of the radio wave absorber, and FIG. 10 is a perspective view of the radio wave absorber of FIG. 9 as viewed from the side of the notch. As shown in FIGS. 9 and 10, a protrusion 6 is provided at the center of an arbitrary side of the pedestal 4 of the pyramid molded body 13, and adjacent to the center of the side facing the protrusion 6. A structure is provided in which a notch 8 for inserting the protrusion 6 of another pyramid molded body 13 to be disposed is provided. Further, the projection 6 is provided with a through hole 7 through which the mounting bracket 9 is inserted.

図１１は、電波吸収体の取り付け要領を示す説明図であり、（ａ）は図１０のＣ−Ｃ線断面を示す電波吸収体の複数個を、垂直壁面Ｗに固定した状態、（ｂ）は（ａ）のＨ部詳細図である。まず、垂直壁面Ｗに、頭部が略Ｌ形の取付金具９を仮付けしておき、下側のピラミッド成形体１３ａの突起部６に設けた通し孔７（孔径は取付金具の頭部を挿通できる大きさ）を前記取付金具９に通して保持し、前記取付金具９を垂直壁面Ｗに締結して下側のピラミッド成形体１３ａを固定する。次に、上側のピラミッド成形体１３ｂの切欠部８を下側ピラミッド成形体１３ａの突起部６に冠着した状態で、上側ピラミッド成形体１３ｂの突起部６の通し孔７に取付金具９を挿通して、上側ピラミッド成形体１３ｂを固定する。この作業を繰り返すことにより、下側から上側に順に電波吸収体を隙間なく配列することができる。なお、本実施形態では、頭部が略Ｌ形の取取付金具９としているが、これに限定されるものではなく、ボルトやビス等の機械的な締結部品を適宜用いることができる。 11A and 11B are explanatory views showing a procedure for attaching the radio wave absorber , wherein FIG. 11A is a state in which a plurality of radio wave absorbers showing a cross section taken along the line C-C in FIG. FIG. 4 is a detailed view of a portion H in (a). First, a mounting bracket 9 having a substantially L-shaped head is temporarily attached to a vertical wall surface W, and a through-hole 7 (hole diameter is the head of the mounting bracket) provided in the protruding portion 6 of the lower pyramid molded body 13a. A size that can be inserted is held through the mounting bracket 9, and the mounting bracket 9 is fastened to the vertical wall surface W to fix the lower pyramid molded body 13 a. Next, with the notch portion 8 of the upper pyramid molded body 13b being attached to the projection 6 of the lower pyramid molded body 13a, the mounting bracket 9 is inserted into the through hole 7 of the projection 6 of the upper pyramid molded body 13b. Then, the upper pyramid molded body 13b is fixed. By repeating this operation, the radio wave absorbers can be arranged in order from the lower side to the upper side without any gaps. In the present embodiment, the mounting bracket 9 has a substantially L-shaped head, but the present invention is not limited to this, and mechanical fastening parts such as bolts and screws can be used as appropriate.

図９から図１１は、図６に示す内部が空洞の台座部付き電波吸収体の固定法を示したが、図２、図５、図７、図８に示す電波吸収体においても、同様にピラミッド成形体の底面または台座部の底面の任意の一辺の中央部に突起部を設け、かつ、該突起部と対向する位置の辺の中央部には、他のピラミッド成形体の突起部を挿入する切欠部を設ければ、同じ要領で電波吸収体を垂直壁面に安全にかつ隙間なく取り付けることができる。   9 to 11 show the fixing method of the radio wave absorber with a pedestal portion whose inside is shown in FIG. 6, but the same applies to the radio wave absorbers shown in FIGS. 2, 5, 7, and 8. Protrusion is provided at the center of any one side of the bottom of the pyramid molded body or the base of the pedestal, and the protrusion of another pyramid molded body is inserted at the center of the side facing the protrusion. If the notch part to be provided is provided, the radio wave absorber can be safely and securely attached to the vertical wall surface in the same manner.

以下、参考例に基づいて本発明による電波吸収体の電波吸収特性等を説明する。 Hereinafter, the radio wave absorption characteristics and the like of the radio wave absorber according to the present invention will be described based on reference examples .

（参考例１）
内部が図３に示すように空洞である、図１に示すピラミッド構造において、ピラミッド高さｐが１５ｃｍ、ピラミッド底面の一辺の長さｄが１０ｃｍ、ピラミッド側壁の厚みｔが１０ｍｍであるピラミッド成形体を粘土素地で形成し、いぶし瓦製造法によりカーボン層を形成してピラミッド形の電波吸収体を作製した。これを９個隙間なく配列して、底面が３０ｃｍ正方の電波吸収体とし、吸収量を測定した。その結果、図１２に示すように、３ＧＨｚから１２ＧＨｚに亘って２０ｄＢ以上の吸収量を示しており、本例による電波吸収体が良好な電波吸収特性を有することが確認された。 ( Reference Example 1 )
In the pyramid structure shown in FIG. 1, the inside is a hollow as shown in FIG. 3, and the pyramid shaped body having a pyramid height p of 15 cm, a side d of the pyramid bottom side of 10 cm, and a pyramid side wall thickness t of 10 mm. Was formed from a clay base, and a carbon layer was formed by the Ibushi tile manufacturing method to produce a pyramidal electromagnetic wave absorber. Nine of them were arrayed without gaps, and the amount of absorption was measured using a radio wave absorber having a bottom surface of 30 cm square. As a result, as shown in FIG. 12, an absorption amount of 20 dB or more was shown over 3 GHz to 12 GHz, and it was confirmed that the radio wave absorber according to this example has good radio wave absorption characteristics.

さらに、ピラミッド高さｐが２０ｃｍ、ピラミッド底面の一辺の長さｄが１５ｃｍになるよう作製した（ピラミッド側壁の厚みｔ、その他の条件は同一）該電波吸収体１個に、５０Ｗの電磁波（周波数２．４５ＧＨｚ）を６０秒照射したところ、特に先端部に近い領域において温度が高くなり、ピラミッド表面の温度は最高で３００℃まで上昇した。電磁波照射を止めて外気中に１０分放置した後に外観検査、吸収量測定を行った。その結果、外観、吸収量とも電磁波照射前と変化はなく、本例による電波吸収体は良好な耐電力特性を有することが確認された。 Furthermore, the pyramid height p was 20 cm, and the length d of one side of the pyramid bottom was 15 cm (the thickness t of the pyramid side wall and other conditions were the same). When irradiated with 2.45 GHz) for 60 seconds, the temperature increased particularly in the region close to the tip, and the temperature of the pyramid surface increased to 300 ° C. at the maximum. After the electromagnetic wave irradiation was stopped and left in the outside air for 10 minutes, an appearance inspection and an absorption amount measurement were performed. As a result, there was no change in the appearance and the amount of absorption before electromagnetic wave irradiation, and it was confirmed that the radio wave absorber according to this example had good power durability characteristics.

（参考例２）
内部が図６のように空洞である、図４に示すピラミッド構造において、ピラミッド高さｐが１５ｃｍ、台座の高さｑが５ｃｍ、台座底面の一辺の長さｄが１０ｃｍ、ピラミッド側壁の厚みｔが１０ｍｍであるピラミッド成形体を粘土素地で形成し、いぶし瓦製造法によりカーボン層を形成して電波吸収体を作製した。これを９個隙間なく配列して底面が３０ｃｍ正方の電波吸収体とし、吸収量を測定した。その結果、図１３に示すように３ＧＨｚから１２ＧＨｚに亘って２０ｄＢ以上の吸収量を示しており、本例による電波吸収体が良好な電波吸収特性を有することが確認された。 ( Reference Example 2 )
In the pyramid structure shown in FIG. 4 in which the inside is a hollow as shown in FIG. 6, the pyramid height p is 15 cm, the pedestal height q is 5 cm, the length d of one side of the pedestal bottom is 10 cm, and the thickness t of the pyramid side wall A pyramid molded body having a thickness of 10 mm was formed from a clay base, and a carbon layer was formed by a method of manufacturing a smoldering tile to produce a radio wave absorber. Nine of these were arrayed without gaps to form a radio wave absorber having a bottom surface of 30 cm square, and the amount of absorption was measured. As a result, as shown in FIG. 13, an absorption amount of 20 dB or more was shown over 3 GHz to 12 GHz, and it was confirmed that the radio wave absorber according to this example has good radio wave absorption characteristics.

（参考例３）
内部が図６のように空洞である、図４に示すピラミッド成形体９個が一体化成形されたピラミッド構造において、ピラミッド高さｐが７ｃｍ、台座の高さｑが３ｃｍ、台座底面の一辺の長さｄが１５ｃｍ、ピラミッド側壁の厚みｔが１０ｍｍであるピラミッド成形体を粘土素地で形成し、いぶし瓦製造法によりカーボン層を形成して電波吸収体を作製した。これを４個隙間なく配列して底面が３０ｃｍ正方の電波吸収体とし、吸収量を測定した。その結果、図１４に示すように３ＧＨｚから１２ＧＨｚに亘って２０ｄＢ以上の吸収量を示しており、本例による電波吸収体が良好な電波吸収特性を有することが確認された。 ( Reference Example 3 )
In the pyramid structure in which nine pyramid molded bodies shown in FIG. 4 are integrally formed as shown in FIG. 4, and the inside is a hollow as shown in FIG. 6, the pyramid height p is 7 cm, the pedestal height q is 3 cm, A pyramid molded body having a length d of 15 cm and a pyramid side wall thickness t of 10 mm was formed from a clay base, and a carbon layer was formed by a smoldering tile manufacturing method to produce a radio wave absorber. Four of these were arranged without gaps to obtain a radio wave absorber having a bottom surface of 30 cm square, and the amount of absorption was measured. As a result, as shown in FIG. 14, the absorption amount was 20 dB or more over 3 GHz to 12 GHz, and it was confirmed that the radio wave absorber according to the present example has good radio wave absorption characteristics.

本発明は、大電力の電磁波を放射するレーダの放射特性評価用、また、大電力の電磁波を電子機器に照射して誤作動状況を評価するイミュニティ評価用の電波暗室の内壁面に装着する電波吸収体として利用可能である。   The present invention relates to a radio wave attached to an inner wall of an anechoic chamber for evaluating radiation characteristics of a radar that emits a high-power electromagnetic wave, and for immunity evaluation for irradiating a high-power electromagnetic wave to an electronic device to evaluate a malfunction state. It can be used as an absorber.

電波吸収体の参考例を示す斜視図である。It is a perspective view which shows the reference example of a radio wave absorber . 図１のＡ−Ａ線断面図（ピラミッド内部を粘土素地で充填形成した構造）である。It is the sectional view on the AA line of FIG. 1 (structure which filled the pyramid inside with the clay base material). 図１のＡ−Ａ線断面図であり、（ａ）はピラミッド内部を空洞にした構造を示したもので、（ｂ）は（ａ）のＤ−Ｄ線拡大断面図である。It is the sectional view on the AA line of FIG. 1, (a) shows the structure which made the inside of a pyramid hollow, (b) is the DD sectional expanded sectional view of (a). 電波吸収体の他の参考例を示す斜視図である。It is a perspective view which shows the other reference example of an electromagnetic wave absorber . 図４のＢ−Ｂ線断面図（ピラミッド内部を粘土素地で充填形成した構造）である。FIG. 5 is a cross-sectional view taken along line BB in FIG. 4 (a structure in which a pyramid is filled with a clay base). 図４のＢ−Ｂ線断面図であり、（ａ）はピラミッド内部を空洞にした構造を示したもので、（ｂ）は（ａ）のＥ−Ｅ線拡大断面図である。It is the BB sectional drawing of FIG. 4, (a) shows the structure which made the inside of a pyramid hollow, (b) is the EE sectional enlarged sectional view of (a). 本発明の一実施形態の電波吸収体を示す斜視図であり、（ａ）は全体斜視図、（ｂ）は放熱孔部分の拡大断面図である。It is a perspective view which shows the electromagnetic wave absorber of one Embodiment of this invention, (a) is a whole perspective view, (b) is an expanded sectional view of a thermal radiation hole part. 電波吸収体の他の参考例を示す斜視図である。It is a perspective view which shows the other reference example of an electromagnetic wave absorber . 電波吸収体の他の参考例を示す斜視図である。It is a perspective view which shows the other reference example of an electromagnetic wave absorber . 図９の電波吸収体を切欠部の側から見た斜視図である。It is the perspective view which looked at the electromagnetic wave absorber of FIG. 9 from the notch part side. 電波吸収体の取り付け要領を示す説明図であり、（ａ）は図１０のＣ−Ｃ線断面を示す電波吸収体の複数個を、垂直壁面Ｗに固定した状態、（ｂ）は（ａ）のＨ部詳細図である。It is explanatory drawing which shows the attachment point of a radio wave absorber , (a) is the state which fixed the several wave absorber which shows the CC line cross section of FIG. 10 to the vertical wall surface W, (b) is (a). FIG. 参考例１の電波吸収特性を示す図である。It is a figure which shows the electromagnetic wave absorption characteristic of the reference example 1 . 参考例２の電波吸収特性を示す図である。It is a figure which shows the electromagnetic wave absorption characteristic of the reference example 2 . 参考例３の電波吸収特性を示す図である。It is a figure which shows the electromagnetic wave absorption characteristic of the reference example 3 .

１、１０、１１、１２、１３、１３ａ，１３ｂ ピラミッド成形体
２ カーボン層
３ 側壁
４ 台座部
５ 放熱孔
６ 突起部
７ 通し孔
８ 切欠部
９ 取付金具
ｄ ピラミッド底面の一辺の長さ
ｐ ピラミッドの高さ
ｑ 台座の高さ
ｔ ピラミッド側壁の厚み
Ｗ 垂直壁面
面Ａ ピラミッド成形体の側壁外面
面Ｂ ピラミッド成形体の側壁内面 1, 10, 11, 12, 13, 13a, 13b Pyramid molded body 2 Carbon layer 3 Side wall 4 Pedestal part 5 Radiation hole 6 Projection part 7 Through hole 8 Notch part 9 Mounting bracket d Length of one side p of pyramid bottom p Height q Height of pedestal t Thickness of pyramid side wall W Vertical wall surface A Side wall outer surface B of pyramid molded body B Side wall inner surface of pyramid molded body

Claims (5)

粘土素地のピラミッド成形体と、
当該粘土素地を成形・乾燥した後、焼成炉内に入れ、約１０００℃に粘土素地を加熱焼成した後、炉内を密閉し、外気と遮断した状態で、炭化水素に富むガスを導入することで燻化処理を行なう、いぶし瓦製造法により、前記粘土素地のピラミッド成形体の表面に形成されたカーボン層とを有し、
前記ピラミッド成形体は、粘土素地を用いて厚みｔを有する側壁で形成されており、該ピラミッド成形体の内部は空洞であると共に、四角形底面が開口されており、側壁内面から側壁外面に貫通する放熱孔が複数個設けられることを特徴とする電波吸収体。 Pyramid molded body of clay body,
After forming and drying the clay matrix, placed in a sintering furnace, after the firing of the clay matrix at about 1000 ° C., was sealed in the furnace, while isolated from the atmosphere, by introducing a gas rich in hydrocarbons in performing Ibushika processing, smoked by tile manufacturing method, and a carbon layer formed on the surface of the pyramid shaped body of the clay matrix,
The pyramid molded body is formed of a side wall having a thickness t using a clay base, the inside of the pyramid molded body is hollow, and a rectangular bottom surface is opened, and penetrates from the side wall inner surface to the side wall outer surface. A radio wave absorber comprising a plurality of heat radiation holes . 前記ピラミッド成形体は、四角形底面の一辺の長さｄとピラミッド高さｐの比（ｐ／ｄ）が１．２〜３．０の範囲であることを特徴とする請求項１に記載の電波吸収体。   2. The radio wave according to claim 1, wherein the pyramid shaped body has a ratio (p / d) of the length d of one side of the quadrangular bottom surface to the pyramid height p in a range of 1.2 to 3.0. Absorber. 前記ピラミッド成形体の下部に、該ピラミッド成形体の底面と同じ形状の断面を有する台座部を設け、かつ該台座部の高さｑとｐの比（ｑ／ｐ）が０．２５〜２．００であることを特徴とする請求項１または２に記載の電波吸収体。   A pedestal portion having a cross section having the same shape as the bottom surface of the pyramid molded body is provided at a lower portion of the pyramid molded body, and a ratio (q / p) between the height q and p of the pedestal portion is 0.25 to 2. The radio wave absorber according to claim 1, wherein the radio wave absorber is 00. 前記ピラミッド成形体は、複数個を一体化して成形することを特徴とする請求項１から３のいずれかに記載の電波吸収体。 The radio wave absorber according to any one of claims 1 to 3, wherein a plurality of the pyramid molded bodies are molded integrally. 前記ピラミッド成形体の底面部は、任意の一辺の中央部に突起部を設け、かつ該突起部と対向する辺の中央部に、他のピラミッド成形体の突起部を挿入する切欠部を設けることを特徴とする請求項１から４のいずれかに記載の電波吸収体。 The bottom surface of the pyramid molded body is provided with a protrusion at the center of any one side and a notch for inserting the protrusion of another pyramid molded body at the center of the side facing the protrusion. The radio wave absorber according to any one of claims 1 to 4 .
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