JP2794293B2 - Radio wave absorption material - Google Patents
Radio wave absorption materialInfo
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- JP2794293B2 JP2794293B2 JP63136494A JP13649488A JP2794293B2 JP 2794293 B2 JP2794293 B2 JP 2794293B2 JP 63136494 A JP63136494 A JP 63136494A JP 13649488 A JP13649488 A JP 13649488A JP 2794293 B2 JP2794293 B2 JP 2794293B2
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- radio wave
- return loss
- band
- plate
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Description
【発明の詳細な説明】 利用産業分野 この発明は、単層の電波吸収体として用いる焼結フェ
ライトに係り、特定組成でかつ高密度のNi−Zn系焼結フ
ェライトとすることにより、例えば、４〜6mmの薄板で
もあっても、広帯域でかつ極めて高い電波吸収能力を発
揮する電波吸収材料に関する。The present invention relates to a sintered ferrite used as a single-layer radio wave absorber, and has a specific composition and a high density of Ni-Zn based sintered ferrite. The present invention relates to a radio wave absorbing material which exhibits a wide band and extremely high radio wave absorbing ability even though it is a thin plate of up to 6 mm.
背景技術 通信技術、航空機等の電波誘導技術の発達、あるいは
TVや各種電気機器等の普及に伴ない、各種電気，電気機
器のノイズフィルター用、制御装置等の誤動作の防止
用、電波反射防止用、電波吸収壁用、さらに電波暗室用
等に、各周波数帯域に整合した電波吸収体が求められ、
種々の材料が提案されている。Background technology Development of communication technology, radio wave guidance technology such as aircraft, or
With the spread of TVs and various electrical equipment, various frequencies are used for noise filters for various electrical and electrical equipment, for preventing malfunctions of control devices, for preventing radio wave reflection, for radio wave absorption walls, and for anechoic chambers. A radio wave absorber matched to the band is required,
Various materials have been proposed.
従来は、導電性を利用する金属板や薄膜、カーボン等
を、ゴムやプラスチックス等で保持したものが一般的で
あった。Conventionally, a metal plate, a thin film, carbon, or the like utilizing conductivity is generally held by rubber, plastics, or the like.
また、磁気的吸収体として知られたカーボニル鉄を用
いたり、さらにゴム等に複合したものや、誘電体損失を
利用した発泡スチロール等が知られていた。Further, carbonyl iron, which is known as a magnetic absorber, is further compounded with rubber or the like, and styrene foam using dielectric loss has been known.
さらに、Ni−Zn系、Mn−Mg−Cu系等のフェライト粉末
をゴム系やシリコン、エポキシ等の高分子化合物と複合
して磁気的吸収体、あるいは電磁気的吸収体となした複
合材料、アルミ等の金属箔片を混入したプラスチックス
材料、導電性繊維を用いたもの等が提案されている。Further, a magnetic absorber or a composite material in which a ferrite powder such as Ni-Zn or Mn-Mg-Cu is combined with a polymer compound such as rubber or silicon or epoxy to form a magnetic absorber or an electromagnetic absorber, aluminum Plastics materials mixed with metal foil pieces, such as those using conductive fibers, and the like have been proposed.
近年では、磁気共鳴現象を利用した焼結フェライト、
すなわち、Mn−Mg系焼結フェライトからなる板に金属板
裏張りを施した構成とすることにより、電波吸収能力に
すぐれ、かつ比較的薄板として利用できるため、実用化
が進んでいる。In recent years, sintered ferrite utilizing magnetic resonance phenomenon,
In other words, by adopting a configuration in which a metal plate backing is applied to a plate made of a Mn-Mg based sintered ferrite, it is excellent in radio wave absorption capability and can be used as a relatively thin plate, so that practical use is progressing.
また、前記の各種材料の組み合わせ、積層した複合材
料も提案されている。Also, a combination of the above-mentioned various materials and a laminated composite material have been proposed.
従来技術の問題点 従来の電波吸収材料は、固有の整合周波数帯域があ
り、例えば、各種の実験や測定に用いる電波暗室は、室
内で発生させた電波を壁で反射させないこと、外部から
の電波を遮断できることが要求され、広帯域における電
波吸収能力にすぐれた材料が求められるため、従来は、
ピラミッド型等の発泡スチロール表面にカーボンを塗布
した構成が利用されていた。Problems with conventional technology Conventional radio-absorbing materials have a unique matching frequency band.For example, an anechoic chamber used for various experiments and measurements must not reflect radio waves generated indoors by walls, Is required to be able to cut off, and materials that have excellent radio wave absorption capability in a wide band are required.
A configuration in which carbon is applied to the surface of a polystyrene foam such as a pyramid has been used.
しかし、従来の電波吸収材料では、電波暗室に要求さ
れる電波反射減衰量を得るには、数百mmの厚みを要する
ため、施工、設置が制限される問題があった。However, the conventional radio wave absorbing material requires a thickness of several hundred mm to obtain the radio wave reflection attenuation required for the radio wave anechoic chamber, so that there is a problem that the construction and installation are limited.
前記焼結フェライトを電波暗室の電波吸収体として用
いるには、電波吸収能力が不足するため、例えば、VHF
帯域で10〜15dBの吸収、減衰量を得るのに厚みを十数mm
以上に増大させるか、発泡スチロールと積層、複合して
用いる必要があり、前者は重量増加が問題となり、後者
はやはり厚みが問題であった。In order to use the sintered ferrite as an electromagnetic wave absorber in an anechoic chamber, the electromagnetic wave absorbing ability is insufficient, for example, VHF
Thickness of more than 10 mm to obtain 10 to 15 dB absorption and attenuation in the band
It is necessary to increase the above or to laminate and composite with Styrofoam. The former has a problem of weight increase, and the latter has also a problem of thickness.
また、各種の制御機器や電子機器に用いられるデバイ
スには、不要信号となる高周波ノイズを遮断するために
電波吸収体の付設が不可欠となっているが、今日の機器
の小型高性能化の要請に伴ない、製造性、加工性がよ
く、薄く小型化可能で電波吸収、減衰量の大きな電波吸
収体が強く求められている。In addition, devices used in various control devices and electronic devices must be equipped with a radio wave absorber to cut off high-frequency noise, which is an unnecessary signal. Accordingly, there is a strong demand for a radio wave absorber that has good manufacturability and workability, is thin and can be miniaturized, and has a large radio wave absorption and attenuation.
発明の目的 この発明は、かかる現状に鑑み、比較的広帯域でかつ
高い反射減衰量を有し、薄板化や小片化が可能で、製造
量産性にすぐれ、電波暗室用や電子デバイス用に最適な
電波吸収材料を目的としている。SUMMARY OF THE INVENTION In view of the present situation, the present invention has a relatively wide band and a high return loss, can be made thin and small, is excellent in mass production, and is most suitable for an anechoic chamber or an electronic device. It is intended for radio wave absorbing materials.
発明の概要 この発明は、広帯域でかつ高い反射減衰量を有する、
すなわち、薄板化や小片化としての利用が可能な電波吸
収材料を目的として、特に焼結フェライトの組成につい
て種々検討した結果、特定組成でかつ高密度のNi−Zn系
焼結フェライトとすることにより、僅か４〜6mmの薄板
で、150〜500MHz帯域における反射減衰量が15dB以上で
かつ200〜300MHz帯域における反射減衰量が20dB以上の
特性が得られることを知見し、この発明を完成したもの
である。SUMMARY OF THE INVENTION The present invention has a broadband and high return loss,
In other words, as a result of various studies on the composition of sintered ferrite, aiming at radio wave absorbing materials that can be used as thinner sheets and smaller pieces, a specific composition and high density Ni-Zn based sintered ferrite was obtained. With a thin plate of only 4 to 6 mm, it was found that the characteristic that the return loss in the 150 to 500 MHz band was 15 dB or more and the return loss in the 200 to 300 MHz band was 20 dB or more, and completed the present invention. is there.
すなわち、この発明は、 Fe2O3 64.80〜66.80wt％ NiO 7.00〜12.45wt％ ZnO 20.60〜23.00wt％ を主成分とし、 あるいはさらに、前記NiOの置換成分としてCuOを5.6wt
％以下含有し、 密度が5.0g/cm3以上の厚さ４〜6mmの板状あるいは管状
体の焼結フェライトからなり、150〜500MHz帯域におけ
る反射減衰量が15dB以上、かつ200〜300MHz帯域におけ
る反射減衰量が20dB以上であることを特徴とする電波吸
収材料である。That is, the present invention is mainly composed of Fe 2 O 3 64.80~66.80wt% NiO 7.00~12.45wt % ZnO 20.60~23.00wt%, or even, 5.6 wt of CuO as a replacement component of the NiO
% Or less, the density is 5.0 g / cm 3 or more, and the thickness is 4 to 6 mm. It is made of sintered ferrite of a plate or tube, and the return loss in the 150 to 500 MHz band is 15 dB or more, and in the 200 to 300 MHz band. It is a radio wave absorbing material having a return loss of 20 dB or more.
発明の構成 組成 この発明による電波吸収材料は、Fe2O3、NiO、ZnOを
主成分とし、各成分が、 Fe2O3 64.80〜66.80wt％ NiO 7.00〜12.45wt％ ZnO 20.60〜23.00wt％ の範囲以外では、6mm以下の薄板で、150〜500MHz帯域に
おける反射減衰量が15dB以上でかつ200〜300MHz帯域に
おける反射減衰量が20dB以上の特性を得ることができな
い。Composition of the Invention Composition The radio wave absorbing material according to the present invention has Fe 2 O 3 , NiO, and ZnO as main components, and each component is Fe 2 O 3 64.80 to 66.80 wt% NiO 7.00 to 12.45 wt% ZnO 20.60 to 23.00 wt% When the thickness of the thin plate is less than 6 mm, it is impossible to obtain the characteristic that the return loss in the 150 to 500 MHz band is 15 dB or more and the return loss in the 200 to 300 MHz band is 20 dB or more.
すなわち、３成分系において、いすれの１成分でも上
記の範囲外となると、電波吸収に必要な磁気損失が小さ
くなり、薄板で目的の帯域における反射減衰量が薄板で
得られなくなる。That is, in the three-component system, if any one of the components is out of the above range, the magnetic loss required for radio wave absorption becomes small, and the thin plate cannot obtain the return loss in the target band.
また、この発明による電波吸収材料においてCuOは、N
iO成分の一部として置換するもので、前記３成分系と同
様の目的帯域での反射減衰量が得られる。置換量が5.6w
t％を越えると、異常粒成長が生じ吸収特性が劣化す
る。すなわち、結晶粒が大きくなりすぎると電波吸収に
必要な磁気損失が小さくなるため、 5.6wt％以下を含有し、好ましくは3.0〜5.0wt％であ
る。In the radio wave absorbing material according to the present invention, CuO is N
By substituting as a part of the iO component, the same return loss in the target band as in the three-component system can be obtained. Replacement amount is 5.6w
Above t%, abnormal grain growth occurs and the absorption characteristics deteriorate. That is, if the crystal grains become too large, the magnetic loss required for radio wave absorption decreases, so that the content is 5.6 wt% or less, preferably 3.0 to 5.0 wt%.
この発明による電波吸収材料は、前記の主成分のほ
か、製造上で不可避な不純物の含有を許容できるが、さ
らに、積極的に以下の元素を添加含有することができ
る。The radio wave absorbing material according to the present invention can contain impurities unavoidable in production in addition to the main components described above, but can further positively contain the following elements.
ZrO2は、焼結性向上のために添加するが、0.1wt％を
越えると、磁気特性が劣化して目的の反射減衰量が薄板
で得られなくなるため、0.1wt％以下含有することがで
き、好ましくは、0.05wt％〜0.1wt％である。ZrO 2 is added to improve sinterability. However, if it exceeds 0.1 wt%, the magnetic properties deteriorate and the desired return loss cannot be obtained with a thin plate. , Preferably 0.05 wt% to 0.1 wt%.
CaOは、異常粒成長抑制のために添加するが、0.3wt％
を越えると、磁気特性が劣化して目的の反射減衰量が薄
板で得られなくなるため、0.3wt％以下含有することが
でき、好ましくは、0.2wt％〜0.3wt％である。CaO is added to suppress abnormal grain growth, but 0.3wt%
If it exceeds 1, the magnetic properties deteriorate and the desired return loss cannot be obtained with a thin plate, so that it can be contained in an amount of 0.3 wt% or less, preferably 0.2 wt% to 0.3 wt%.
SiO2は、高周波数領域における磁気特性の向上のため
に添加するが、0.3wt％を越えると、異常粒成長が生じ
磁気特性が劣化するため0.3wt％以下含有することがで
き、好ましくは、0.15wt％〜0.3wt％である。SiO 2 is added to improve the magnetic properties in the high frequency region. However, if it exceeds 0.3 wt%, abnormal grain growth occurs and the magnetic properties deteriorate, so it can be contained at 0.3 wt% or less. 0.15 wt% to 0.3 wt%.
CoOは、目的の周波数領域（バンド幅）を得るため
に、0.3wt％以下含有することができ、好ましくは、0.1
5wt％〜0.3wt％である。CoO can be contained in an amount of 0.3 wt% or less in order to obtain a target frequency region (bandwidth), and preferably 0.1 wt% or less.
5 wt% to 0.3 wt%.
性状・組織 この発明によるNi−Zn系焼結フェライトは、組成的に
は、 （NiO）ｘ・（ZnO）ｙ・（CuO）ｚ・Fe2O3、（ｘ＋ｙ＋
ｚ≦１） の一般式で示され、その結晶構造はスピネル型である。Properties Tissue Ni-Zn-based sintered ferrite according to the present invention, the compositional, (NiO) x · (ZnO ) y · (CuO) z · Fe 2 O 3, (x + y +
z ≦ 1), and its crystal structure is a spinel type.
また、この発明によるNi−Zn系焼結フェライトは、す
ぐれた特性を得るには、少なくとも5.0g/cm3の密度が必
要である。好ましくは5.0g/cm3〜5.3g/cm3である。The Ni-Zn sintered ferrite according to the present invention requires a density of at least 5.0 g / cm 3 in order to obtain excellent characteristics. Preferably from 5.0g / cm 3 ~5.3g / cm 3 .
この発明において、得られる反射減衰量は、組成の違
いや製造過程の違いによる差より、材料厚み等の寸法、
形状の違いによる差が大きく、組成の違い、要求される
周波数帯域及び反射減衰量に応じて、適宜選定するとよ
い。In the present invention, the obtained return loss is determined by the difference due to the difference in the composition or the manufacturing process.
The difference due to the difference in shape is large, and it may be appropriately selected according to the difference in composition, the required frequency band, and the return loss.
例えば、この発明によるNi−Zn系焼結フェライトを、
タイル状で用いる場合、組成が、 Fe2O3 66.60〜66.80wt％,NiO 10.90〜11.10wt％、 ZnO 20.60〜22.40wt％ あるいは、 Fe2O3 64.80〜65.20wt％、NiO 9.30〜9.7wt％、 CuO 4.50〜4.9wt％、ZnO 20.60〜21.0wt％のものを、 厚み４〜6mmで、任意の形状寸法に成型し、焼結したま
ま、裏張り金属板にCu板あるいはAl板を用い、これを所
要の位置に敷設あるいは貼着する。For example, Ni-Zn based sintered ferrite according to the present invention,
When used in tile form, the composition is Fe 2 O 3 66.60-66.80 wt%, NiO 10.90-11.10 wt%, ZnO 20.60-22.40 wt% or Fe 2 O 3 64.80-65.20 wt%, NiO 9.30-9.7 wt% , CuO 4.50 ~ 4.9wt%, ZnO 20.60 ~ 21.0wt%, 4 ~ 6mm thick, molded into any shape and size, sintered and used as the backing metal plate using Cu plate or Al plate, This is laid or attached at the required position.
また、この発明によるNi−Zn系焼結フェライトを、管
状で用いる場合、例えば、電磁波を発生するコード等を
包囲するため、前記組成のものを、厚み４〜6mmで、任
意寸法の管状に成型し、焼結したまま、裏張り金属板に
Cu板あるいはAl板を用いて使用できる。When the Ni-Zn sintered ferrite according to the present invention is used in the form of a tube, for example, in order to surround a cord or the like that generates electromagnetic waves, the above-mentioned composition is molded into a tube having a thickness of 4 to 6 mm and an arbitrary size. And then, as it is sintered,
It can be used by using Cu plate or Al plate.
製造法 この発明による電波吸収材料であるNi−Zn系焼結フェ
ライトは、 純度99.2wt％以上、平均粒度0.6μｍのFe2O3 純度99.5wt％以上、平均粒度1.6μｍのZnO 純度98.5wt％以上、平均粒度0.6μｍのNiO 純度99.2wt％以上、平均粒度0.8μｍのCuO の原料粉末を目的組成となるように配合し、十分に混合
した後、混合粉を、900℃、３時間、大気中で仮焼す
る。Manufacturing method Ni-Zn based sintered ferrite which is a radio wave absorbing material according to the present invention has a purity of 99.2 wt% or more, an average particle size of 0.6 μm Fe 2 O 3 purity of 99.5 wt% or more, and an average particle size of 1.6 μm ZnO purity 98.5 wt% As described above, a raw material powder of CuO having an average particle size of 0.6 μm, NiO purity of 99.2 wt% or more and an average particle size of 0.8 μm is blended so as to have a desired composition, and after sufficiently mixing, the mixed powder is subjected to air at 900 ° C. for 3 hours. Calcinate inside.
得られた仮焼粉を、ボールミルにて平均粒度1.0〜1.6
μｍまで湿式粉砕した後、PVA等のバインダーを0.6〜1.
0wt％加え、スプレードライヤーにより、50〜100μｍの
造粒粉を作成した。The calcined powder obtained, average particle size 1.0 to 1.6 in a ball mill
After wet pulverization to μm, a binder such as PVA is added to 0.6-1.
0 wt% was added, and a granulated powder of 50 to 100 μm was prepared by a spray dryer.
この造粒粉を成型装置により、600〜1000kg/cm2の圧
力で任意形状に成型する。This granulated powder is molded into an arbitrary shape by a molding device at a pressure of 600 to 1000 kg / cm 2 .
さらに、成型体を、1100〜1200℃、３時間、大気中で
焼結する。Further, the molded body is sintered at 1100 to 1200 ° C. for 3 hours in the air.
実 施 例 実施例１ 原料粉末を下記組成となるように配合混合した後、平
均粒度１μｍの成型用粉末となし、成形装置により管状
成型体となした。EXAMPLES Example 1 After mixing and mixing the raw material powders so as to have the following composition, the mixture was formed into a molding powder having an average particle size of 1 μm, and formed into a tubular molded body by a molding apparatus.
成型体を、1230℃×２時間、大気雰囲気にて焼結し、
外径50mm×内径13mmの焼結体を得た。The molded body is sintered at 1230 ° C for 2 hours in air atmosphere,
A sintered body having an outer diameter of 50 mm and an inner diameter of 13 mm was obtained.
さらに焼結体より、厚み5mmのリング状試験片を切出
し、電波吸収特性の測定を行なった。Further, a ring-shaped test piece having a thickness of 5 mm was cut out from the sintered body, and the radio wave absorption characteristics were measured.
電波吸収特性の測定は、第１図に示す如く、同軸管
（１）の一方端をショート板（２）でショートし、該シ
ョート板（２）の前に前記リング状試験片（４）を挿入
し、装入前後の電波の反射吸収特性をネットワーク・ア
ナライザー（５）にて測定することにより実施した。As shown in FIG. 1, one end of the coaxial tube (1) is short-circuited with a short plate (2), and the ring-shaped test piece (4) is placed in front of the short plate (2). The measurement was performed by inserting and measuring the reflection and absorption characteristics of radio waves before and after loading with a network analyzer (5).
同軸管（１）は、外径40mm×内径30mm×150mmの円筒
体からなり、13mmΦの円柱（３）を40Φ×3mmのショー
ト板（２）に同軸に立設し、円筒体内に円柱を挿入しか
つショート板（２）で一端が閉塞されるように同軸配置
した構成で、全て銅製からなる。The coaxial tube (1) consists of a cylindrical body with an outer diameter of 40mm x inner diameter of 30mm x 150mm. A 13mmΦ cylinder (3) is set up coaxially on a 40Φx3mm short plate (2), and the cylinder is inserted into the cylinder. And is coaxially arranged so that one end is closed by the short plate (2), and all are made of copper.
比較試験片として、市販のMn−Mg系焼結フェライトブ
ロックより、前記寸法の試験片を切出して測定した。As a comparative test piece, a test piece having the above dimensions was cut out from a commercially available Mn-Mg-based sintered ferrite block and measured.
試験結果は、第２図の周波数と減衰特性との関係のグ
ラフ（dB−ｆ特性図）に示す。The test results are shown in the graph (dB-f characteristic diagram) of the relationship between the frequency and the attenuation characteristic in FIG.
発明の効果 この発明によるNi−Zn系焼結フェライトは、僅か４〜
6mmの薄板で、 150〜500MHz帯域における反射減衰量が15dB以上でかつ2
00〜300MHz帯域における反射減衰量が20dB以上の特性が
得られ、また、製造性、加工性がよく、薄く小型化ある
いは任意形状に成形可能で、電波暗室用や電子デバイス
用に最適な電波吸収，減衰量の大きな電波吸収体が得ら
れる。 Effect of the Invention The Ni-Zn based sintered ferrite according to the present invention has only 4 ~
6mm thin plate, return loss in the 150-500MHz band is more than 15dB and 2
Characteristic with a return loss of 20 dB or more in the 00 to 300 MHz band is obtained, and it has good manufacturability and workability, and can be made thin and compact or can be formed into any shape, making it ideal for use in anechoic chambers and electronic devices Thus, a radio wave absorber having a large attenuation can be obtained.
第１図は実施例における試料の電波反射吸収特性の測定
装置の説明図である。 第２図は周波数と減衰特性との関係を示すグラフ（dB−
ｆ特性図）である。 １……同軸管、２……ショート板、３……円柱、４……
試験片、 ５……ネットワーク・アナライザー。FIG. 1 is an explanatory diagram of an apparatus for measuring the radio wave reflection and absorption characteristics of a sample in an embodiment. FIG. 2 is a graph showing the relationship between frequency and attenuation characteristics (dB-
FIG. 1 ... coaxial tube, 2 ... short plate, 3 ... cylinder, 4 ...
Specimen, 5 Network analyzer.
フロントページの続き (72)発明者 景山 恵介 大阪府三島郡島本町江川２丁目15―17 住友特殊金属株式会社山崎製作所内 (56)参考文献 特開 昭57−80461（ＪＰ，Ａ) 特開 昭51−31889（ＪＰ，Ａ) (58)調査した分野(Int.Cl.6，ＤＢ名) H01F 1/00 C04B 35/30Continuation of the front page (72) Inventor Keisuke Kageyama 2- 15-17 Egawa, Shimamoto-cho, Mishima-gun, Osaka Prefecture Sumitomo Special Metals Co., Ltd. Yamazaki Works (56) References JP-A-57-80461 (JP, A) JP-A Sho 51-31889 (JP, A) (58) Fields investigated (Int. Cl. 6 , DB name) H01F 1/00 C04B 35/30
Claims (2)
体の焼結フェライトからなり、150〜500MHz帯域におけ
る反射減衰量が15dB以上でかつ200〜300MHz帯域におけ
る反射減衰量が20dB以上であることを特徴とする電波吸
収材料。1. A plate or tube having a thickness of 4 to 6 mm having a main component of Fe 2 O 3 64.80 to 66.80 wt% NiO 7.00 to 12.45 wt% ZnO 20.60 to 23.00 wt% and a density of 5.0 g / cm 3 or more. A radio wave absorbing material comprising a body of sintered ferrite, wherein a return loss in a 150 to 500 MHz band is 15 dB or more and a return loss in a 200 to 300 MHz band is 20 dB or more.
有し、 密度が5.0g/cm3以上の厚さ４〜6mmの板状あるいは管状
体の焼結フェライトからなり、150〜500MHz帯域におけ
る反射減衰量が15dB以上でかつ200〜300MHz帯域におけ
る反射減衰量が20dB以上であることを特徴とする電波吸
収材料。Wherein the Fe 2 O 3 64.80~66.80wt% NiO 7.00~12.45wt % ZnO 20.60~23.00wt% main component, further, the CuO as a replacement component of the NiO containing less 5.6 wt%, density 5.0 g / cm 3 or more consists thickness 4~6mm plate or sintered ferrite of the tubular body, the reflection attenuation amount in the return loss at the 15dB or more and 200~300MHz band in 150~500MHz band is more than 20dB An electromagnetic wave absorbing material characterized by the above.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63136494A JP2794293B2 (en) | 1988-06-02 | 1988-06-02 | Radio wave absorption material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63136494A JP2794293B2 (en) | 1988-06-02 | 1988-06-02 | Radio wave absorption material |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01305503A JPH01305503A (en) | 1989-12-08 |
| JP2794293B2 true JP2794293B2 (en) | 1998-09-03 |
Family
ID=15176474
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63136494A Expired - Lifetime JP2794293B2 (en) | 1988-06-02 | 1988-06-02 | Radio wave absorption material |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2794293B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6146545A (en) * | 1998-12-04 | 2000-11-14 | Tdk Corporation | Radio wave absorbent |
| WO2008047854A1 (en) | 2006-10-19 | 2008-04-24 | Hitachi Metals, Ltd. | Radio wave absorption material and radio wave absorber |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR930011547B1 (en) * | 1991-08-13 | 1993-12-10 | 한국과학기술연구원 | Electric wave absorber |
| KR930011549B1 (en) * | 1991-08-13 | 1993-12-10 | 한국과학기술연구원 | Electric wave absorber |
| JP4885894B2 (en) * | 2008-02-25 | 2012-02-29 | Ｊｆｅケミカル株式会社 | NiCuZn ferrite tiles for radio wave absorption |
| JP5537064B2 (en) * | 2009-04-21 | 2014-07-02 | 矢崎総業株式会社 | Inner diameter measuring device |
| JP2017014047A (en) * | 2015-06-30 | 2017-01-19 | Tdk株式会社 | Ferrite sintered body, and ferrite core |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5133273A (en) * | 1974-09-12 | 1976-03-22 | Takeyoshi Myahara | Shindobutsutai no shijisochi |
| JPS5219046A (en) * | 1975-08-04 | 1977-01-14 | Tdk Corp | Microwave absorver |
-
1988
- 1988-06-02 JP JP63136494A patent/JP2794293B2/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6146545A (en) * | 1998-12-04 | 2000-11-14 | Tdk Corporation | Radio wave absorbent |
| WO2008047854A1 (en) | 2006-10-19 | 2008-04-24 | Hitachi Metals, Ltd. | Radio wave absorption material and radio wave absorber |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01305503A (en) | 1989-12-08 |
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