WO2002043459A1 - Absorbeur d'ondes radioelectriques - Google Patents
Absorbeur d'ondes radioelectriques Download PDFInfo
- Publication number
- WO2002043459A1 WO2002043459A1 PCT/JP2001/010058 JP0110058W WO0243459A1 WO 2002043459 A1 WO2002043459 A1 WO 2002043459A1 JP 0110058 W JP0110058 W JP 0110058W WO 0243459 A1 WO0243459 A1 WO 0243459A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- radio wave
- wave absorber
- magnetic
- radio
- electromagnetic
- Prior art date
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F10/00—Thin magnetic films, e.g. of one-domain structure
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K9/00—Screening of apparatus or components against electric or magnetic fields
- H05K9/0073—Shielding materials
- H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
- H05K9/0083—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising electro-conductive non-fibrous particles embedded in an electrically insulating supporting structure, e.g. powder, flakes, whiskers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y25/00—Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/0036—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties showing low dimensional magnetism, i.e. spin rearrangements due to a restriction of dimensions, e.g. showing giant magnetoresistivity
- H01F1/0045—Zero dimensional, e.g. nanoparticles, soft nanoparticles for medical/biological use
- H01F1/0063—Zero dimensional, e.g. nanoparticles, soft nanoparticles for medical/biological use in a non-magnetic matrix, e.g. granular solids
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K9/00—Screening of apparatus or components against electric or magnetic fields
- H05K9/0073—Shielding materials
- H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
- H05K9/0088—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising a plurality of shielding layers; combining different shielding material structure
Definitions
- the present invention relates to a radio wave absorber that absorbs unnecessary electromagnetic waves, and more particularly to a light and thin radio wave absorber for absorbing high-frequency electromagnetic waves.
- radio waves such as wireless LANs (Local Area Networks) and automatic highway tolling systems
- wireless LANs Local Area Networks
- automatic highway tolling systems Is a disturbing wave
- radio wave absorber to absorb the disturbing wave and facilitate communication.
- electromagnetic waves in the 2.45 GHz band are used in various electronic devices such as microwave ovens, personal digital assistants, wireless LANs, and B1uetooth, and these electronic devices may malfunction mutually. It is important that communication be carried out smoothly.
- ⁇ Z 6 wavelength of the electromagnetic wave
- a radio wave absorber for a nearby electromagnetic field converts the energy of the incident electromagnetic wave into heat and absorbs it.
- This energy conversion includes the loss term ⁇ "(complex relative permittivity) of the relative permittivity of the radio wave absorber.
- the imaginary component of the relative permeability and the loss term ⁇ ′′ (the imaginary component of the complex relative permeability) are related.
- ⁇ 1/2 ⁇ ⁇ . ⁇ "IE 2 I + 1/ 2 ⁇ Q" IH 2 I (1) formula (1), P is the radio wave absorption energy per unit volume [WZ! 11 3], £ 0 the electromagnetic wave of the angular frequency (2 ⁇ , F: frequency of electromagnetic wave), ⁇ .
- the material having a higher loss has a higher radio wave absorption capacity.
- the value of "" for electromagnetic waves in the high-frequency band of 1 GHz or higher is about 10, which is not sufficient absorption performance.
- such an impedance-matched electromagnetic wave absorber is designed so that the material constant satisfies the following equation (2), and by controlling the thickness of the electromagnetic wave absorbing layer, the impedance at the target frequency is reduced. Realize the reflection.
- i Imaginary unit
- d Thickness of radio wave absorber
- oxide-based magnetic materials such as ferrite, which have high electrical resistance.
- ferrite oxide-based magnetic materials
- many are used.
- rubber ferrite is widely used, and among ferrites, spinel ferrite is frequently used in the MHz band and hexagonal ferrite is often used in the GHz band.
- the matching frequency and the matching thickness are determined.
- the thickness can be calculated from equation (2). It was about 1 cm, and a radio wave absorber of this thickness was conventionally used.
- the magnetic layer has a single-layer structure using a magnetic material of Ba (F e, T i, M n) u ⁇ 12 which is a kind of hexagonal ferrite.
- the thickness of the electromagnetic wave absorber is about 3 mm for electromagnetic waves near 5 GHz.
- a thin film material containing Co is known, and is disclosed in, for example, Japanese Patent Application Laid-Open No. H10-241938.
- a Co—Ni—A1 thin film or the like two or more types of magnetic fine particles whose grain size is controlled to about 4 to 7 nm and a very thin ceramic film grain boundary surrounding the magnetic fine particles are used.
- a Dara-niura structure consisting of a fine structure, both high magnetic permeability and high electrical resistance are achieved.
- the present invention has been made in view of such problems, and an object of the present invention is to provide a thinner radio wave absorber having high absorption performance for high-frequency electromagnetic waves. Disclosure of the invention
- the present invention provides a radio wave absorber for absorbing unnecessary electromagnetic waves, comprising one or more magnetic materials including a magnetic material having a microstructure having a controlled particle size of 1 to 100 nm.
- a radio wave absorber characterized by comprising a layer is provided.
- the use of a magnetic material having a fine structure in which the particle size is controlled to 1 to 100 nm for the magnetic layer enables high electric resistance and high relative permeability to high-frequency electromagnetic waves. It has a high magnetic susceptibility, can enhance absorption performance, and can be made thinner and lighter.
- a thin impedance-matched electromagnetic wave absorber for electromagnetic fields relatively far away from the wave source by ⁇ Z 6 or more. can also be configured.
- the magnetic layer is formed by dispersing a powder of a magnetic material containing at least one of Fe, Co, and Ni or an alloy containing Mn in a polymer material.
- FIG. 1 shows a schematic view of the magnetic material used in the present invention.
- FIG. 2 is a diagram showing a structure of a radio wave absorption sheet for a near electromagnetic field.
- FIG. 3 is a cross-sectional view of a radio wave absorption sheet for a far electromagnetic field.
- FIG. 4 is a cross-sectional view of a multi-layer radio wave absorbing sheet for a far electromagnetic field.
- FIG. 5 is a diagram showing a radio wave absorption characteristic according to a design example of a radio wave absorption sheet.
- FIG. 6 is a diagram showing the absorption characteristics for each frequency in the design example of the radio wave absorption sheet.
- FIG. 7 is a diagram showing an example in which the SAR suppressor of the present invention is applied to a mobile phone.
- FIG. 8 is a diagram schematically showing an application example of the present invention as a cavity resonance suppressor.
- FIG. 9 is a diagram showing the structure of a pyramid-type radio wave absorber. BEST MODE FOR CARRYING OUT THE INVENTION
- FIG. 1 shows a schematic diagram of the magnetic material used in the present invention.
- fine magnetic particles 1a whose particle size is controlled to 1 to 100 nm are slightly in contact with each other via a very thin grain boundary 1b. Is shown.
- a material having a higher loss in an electromagnetic wave absorber has a higher absorption capacity. Therefore, the material used in the present invention needs to have a high relative magnetic permeability up to a high frequency region. When a high-frequency magnetic field is applied to the magnetic material 1 and the magnetic particles 1 are in contact with each other, the magnetic flux passes through the area of the magnetic material 1 and the relative magnetic permeability increases.
- the electromagnetic wave absorber of the present invention although the magnetic materials 1 are slightly in contact with each other, a very thin grain boundary 1b of a high-resistance compound is arranged between the magnetic particles 1a. And the higher frequency band A material having a high relative magnetic permeability up to the range and a high loss is obtained. However, if the grain boundaries 1b become too thick and the magnetic particles 1a are isolated, superparamagnetism may occur.
- Figure 2 shows the structure of the radio wave absorption sheet for the near electromagnetic field.
- the electromagnetic wave absorption sheet 2 shown in FIG. 2 is formed by forming a magnetic layer containing the above-described magnetic material in a sheet shape. The purpose is to absorb it. As described above, the energy of the electromagnetic wave is converted into heat with respect to the nearby electromagnetic field, and the energy conversion includes the loss term ⁇ "of the relative permittivity of the radio wave absorber and the loss term" of the relative permeability ". Related You. When an electromagnetic wave is incident on a material having such a loss, the energy of the electromagnetic wave is converted into heat and absorbed according to the above-mentioned equation (1). According to this equation (1), in the absorption of electromagnetic waves using the magnetic loss ", the larger the magnetic field strength H, the greater the amount of absorption. Therefore, the radio wave absorber is located as close to the wave source as possible. It is desirable to be installed in
- the radio wave absorbing sheet 2 shown in FIG. 2 for example, a method is used in which the above-described magnetic material is powdered, and the magnetic material is combined with a polymer material to form a sheet.
- the above-mentioned magnetic material having a nano-dual double structure is prepared as a powder material.
- Such a powder material is dispersed in a polymer material at a volume filling ratio of 30 to 60%, and kneaded with three rolls to produce a paste-like sample, which is then subjected to the Doc Yuichi blade method. It is adjusted to a predetermined thickness and processed into a sheet.
- the polymer material chlorinated polyethylene, rubber-based material, ABS resin, biodegradable polylactic acid, or the like can be used, and even when cured using a thermosetting resin, a photocurable resin, or the like. Good. Further, concrete ceramics or the like may be used instead of the polymer.
- FIG. 3 is a cross-sectional view of a radio wave absorbing sheet for a distant electromagnetic field.
- the electromagnetic wave absorbing sheet 3 shown in FIG. 3 is an impedance-matching type electromagnetic wave absorber, and has a structure in which a magnetic layer 31 and a conductor 32 are fixed to the surface of the magnetic layer 31 opposite to the electromagnetic wave incident surface. Have.
- the material and method used to form the magnetic layer 31 are the same as those for the magnetic layer of the radio wave absorbing sheet 2 described above.
- a metal film such as an aluminum foil, a carbon film, and an ITO film can be used. These are formed as a vapor-deposited film or a sputtered film.
- the metal surface of the structure on which the radio wave absorbing sheet 3 is installed may be configured to correspond to the backing conductor.
- a radio wave absorber having a multilayer structure including a magnetic layer made of the above material may be used as the impedance matching type radio wave absorber.
- Fig. 4 shows a cross-sectional view of a multi-layer radio wave absorption sheet for far electromagnetic fields.
- the electromagnetic wave absorbing sheet 4 shown in FIG. 4 has a dielectric layer 41 made of a dielectric material and a magnetic layer 42 laminated from the electromagnetic wave incident surface side as an electromagnetic wave absorbing layer, and a conductor 43 is lined with this. It has a structure.
- the impedance of the incident surface is reduced by providing a magnetic layer 42 having a high relative permeability on the side of the backed conductor 43 and a dielectric layer 41 on the incident surface side of the electromagnetic wave. , The amount of reflection is suppressed, and the phase of the reflected wave can be easily matched.
- the dielectric layer 41 is formed by dispersing a dielectric material in a polymer matrix. Generated.
- B a O- T i 0 2 system, P b T i ⁇ 3 - P b Z r 0 3 system (PZT system), P B_ ⁇ 2 - L i 2 0 3 - Z r 0 2 - T i 0 2 system (PLTZ system), M g T i O 3 - C a T i 0 3 system, B a M g Bok x T a x O 3 system, BZ n WINCH x T a x ⁇ 3 system, B a 2 T i 0 2 system, Z r 1-X S n X T i ⁇ 4 system, B a ⁇ 1 N d 2 ⁇ 3 — T i O 2 system, P b ⁇ C a x Z r 0 3 system , P b T i 0 3 - P r Z r 0 3 - P b B, (., x) B 2 a (x) O 3 system can
- a design example of the radio wave absorption sheet 4 having the structure shown in FIG. 4 is shown.
- Fig. 5 shows the radio wave absorption characteristics of this design example.
- the thickness of the dielectric layer 41 is 200 m
- the real part ⁇ ′ and the imaginary part ⁇ ′′ of the complex relative permittivity are 100, 0.2, respectively, and the real part ′ and the imaginary part of the complex relative permeability.
- the part ⁇ ′′ is 1
- the thickness of the magnetic layer 42 is 200
- the real part ⁇ ′ and the imaginary part ⁇ ′′ of the complex relative permittivity are 110, 0.2, respectively.
- the figure plots the return loss when the complex relative magnetic permeability of the magnetic layer 42 is changed as the reflection characteristic of such a material.
- the relative magnetic permeability ⁇ 4 It can be seen that by using a material having a value near 0 — 30 j, good absorption performance of ⁇ 20 dB or more can be obtained for electromagnetic waves in the 2.2 GHz band.
- Fig. 6 shows the absorption characteristics for each frequency in the above design example.
- an FeCo-based material having a nano dura Can As a magnetic material having a relative dielectric constant and a relative magnetic permeability value as in the above design example, an FeCo-based material having a nano dura Can be used. In FIG. 6, such a magnetic material is used for the magnetic layer 42, and the dielectric layer 41 and the magnetic layer 42 take on the values shown in the design example.
- the radio wave absorbing sheet 2 shown in FIG. 2 can be used by installing it inside the housing of various electronic devices, for example, to prevent unnecessary radiation. It can also be used as a prepreg used for bonding substrates. This makes it possible to efficiently take measures against unwanted radiation in a lightweight, space-saving, and attenuate conduction noise.
- the specific absorption rate SAR (Speci He Absorption Rate), which is the local absorption power of electromagnetic waves per kilogram of body weight, has been defined as a measure of the amount of absorption of electromagnetic waves emitted by electronic devices by the human body.
- SA R Specific absorption Rate
- the radio wave absorber of the present invention has a high /”. Therefore, the effect as a SAR suppressor can be expected.
- FIG. 7 shows an example of application of the SAR suppressor to a mobile phone.
- FIG. 7 shows a side sectional view of the mobile phone 7.
- the mobile phone 7 includes a circuit board 72 on which a wireless circuit section 71 is mounted, a conductive shield case 73 for housing them, an antenna 74 connected to the circuit board 72, and a liquid crystal display section. 75, an input pad 76 for input, and an external housing 77 made of a plastic material or the like.
- suppressing the surface current flowing on the shield case 73 is effective for suppressing the SAR.
- a soft magnetic sheet 78 formed by combining a magnetic material having a nano-dura-double-structure and a polymer material, which is configured in the same manner as the radio wave absorbing sheet 2 shown in FIG. It was installed above shield case 73.
- the soft magnetic sheet 78 was made of a FeCo-based material as a magnetic material and polyvinyl chloride as a base material, and was made to have a size of 10 X 10 X 2 (mm).
- the soft magnetic sheet 78 functions as a very high performance SAR suppressor that suppresses only SAR without hindering the characteristics of the antenna 74.
- the electromagnetic wave absorber of the present invention since the electromagnetic wave absorber of the present invention has a high magnetic loss, it is also effective in suppressing cavity resonance in which an external housing or the like resonates due to electromagnetic waves radiated from inside the electronic device such as a circuit board.
- the external housing 81 shown in FIG. 8 is for accommodating, for example, a computer device such as a personal computer, a video camera, or the like, and is made of plastic or plated metal, or A 1, Mg. And the like.
- a magnetic material having a nano-granular structure and a polymer material are formed on the inner surface in the same manner as the radio wave absorber 3 shown in FIG.
- the soft magnetic sheet 82 By sticking the soft magnetic sheet 82 formed as described above, the soft magnetic sheet 82 functions as a cavity resonance suppressor.
- the soft magnetic sheet 82 for example, when the thickness is about 0.3 to 2 mm, good absorption performance for electromagnetic waves with a frequency of about 30 MHz to 2.5 GHz can be obtained. it can.
- the cavity resonance suppressor is provided in the outer casing 81 or the like, a relatively large area is required, but the soft magnetic sheet 82 can be made thinner than the conventional one. However, the weight of the outer casing 81 can be reduced.
- the radio wave absorber using the above magnetic material is not limited to such a form. It can take the form of an implementation.
- a material for forming the magnetic layer may be prepared in the form of a paste.
- a powder of a magnetic material having a nano-dura structure is prepared, and this powder is used as a thermoplastic resin (thermosetting resin), a photo-curing resin, or an ultraviolet-curing resin. Or knead with a material such as a room temperature curable resin. At this time, IPA (isopropyl alcohol) or another organic solvent may be used as a solvent depending on the type of resin.
- the volume filling ratio of magnetic powder is 20 to 50%, It is produced by adjusting so as not to lose liquidity.
- the magnetic layer is formed with high fluidity
- the magnetic layer is formed by spraying on the surface of the target structure with a sprayer, or by applying it with a brush or the like, or by a method such as injection molding. Is also good. This makes it possible to easily form a radio wave absorber having good absorption performance for high-frequency electromagnetic waves into various shapes according to the installation method.
- a radio wave absorber made of a material in the form of a paste there is a pyramid type radio wave absorber used for a radio wave room or the like.
- Fig. 9 shows the structure of a pyramid-type electromagnetic wave absorber.
- an impedance matching type is provided by providing a plurality of three-dimensional vilamid-shaped magnetic layers 92 on the surface of a conductor such as a copper plate 91 provided on the wall surface.
- a radio wave absorber is configured.
- the magnetic layer 92 is formed by performing injection molding using a paste-like material generated by the above-described method.
- the absorption characteristics of such a viramid type electromagnetic wave absorber 9 are considered to gradually change from the top to the bottom of the pyramid shape, it has an absorption performance for electromagnetic waves in a wide frequency range.
- the viramid shape of the magnetic layer 92 is not limited to the quadrangular pyramid shape as shown in FIG. 9, but may be a conical shape or a comb shape. .
- this paste-like material can be introduced into a dispenser and used as a sealing resin for an IC or the like.
- an RF radio frequency
- e nc y This has the effect of preventing mutual interference between the signal and the BB (Base Band) signal.
- the particles are filled into a sealing resin such as an epoxy resin or a molding resin at a volume ratio of 30 to 50%, and are produced by a method such as injection molding or potting.
- a sealing resin such as an epoxy resin or a molding resin at a volume ratio of 30 to 50%
- the thickness of the sealing resin to be formed is about 0.5 to 2 mm, it is possible to obtain an absorption performance for electromagnetic waves having a frequency of about 30 MHz to 2.5 GHz.
- the semiconductor-like resin or the mold-sealing resin can be provided with a radio wave absorbing function by using the heat-stable material, so that there is no need to provide a separate space for installing a radio wave absorber around the resin.
- the size of the device is reduced, and the manufacturing cost is reduced.
- a soft magnetic sheet 82 is formed as a cavity resonance suppressor, but by using a paste-like material, the external housing 81 is required.
- the other method is to knead a magnetic material having a nano-dualranular structure in the polymer material constituting the outer casing 81, and form the outer casing 81 itself by injection molding. It is possible to form a cavity resonance suppressor.
- the outer casing 8 1 itself can be used as a cavity resonance suppressor, it is possible to simplify a post-measure in a device manufacturing process for unnecessary electromagnetic waves and to suppress a manufacturing cost. In addition, the size of the device can be reduced.
- the above materials can be used to realize a radio wave absorbing substrate, radio wave absorbing glue, etc., with the product itself having radio wave absorbing performance, and mix magnetic material into transparent resin material while adjusting to maintain transparency. You This makes it possible to produce radio wave absorbing glass.
- the use of the magnetic material having a fine structure in which the particle size is controlled to 1 to 100 nm for the magnetic layer makes the radio wave absorber highly resistant to high-frequency electromagnetic waves. It has electric resistance and high relative magnetic permeability, improves absorption performance, and can be made thinner and lighter.
- a conductor is fixed to the surface of the magnetic layer opposite to the incident surface of the electromagnetic wave, a thin impedance matching with respect to a relatively distant electromagnetic field ⁇ / 6 or more from the wave source is achieved. It is also possible to constitute a type of electromagnetic wave absorber.
- the magnetic layer is formed by dispersing a powder of a magnetic material containing at least one of Fe, Co, and Ni or an alloy containing Mn in a polymer material.
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Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP01982830A EP1274293A1 (en) | 2000-11-21 | 2001-11-16 | Radio-wave absorber |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2000354254A JP2002158484A (ja) | 2000-11-21 | 2000-11-21 | 電波吸収体 |
JP2000-354254 | 2000-11-21 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2002043459A1 true WO2002043459A1 (fr) | 2002-05-30 |
Family
ID=18826883
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2001/010058 WO2002043459A1 (fr) | 2000-11-21 | 2001-11-16 | Absorbeur d'ondes radioelectriques |
Country Status (6)
Country | Link |
---|---|
US (1) | US20030107025A1 (ja) |
EP (1) | EP1274293A1 (ja) |
JP (1) | JP2002158484A (ja) |
KR (1) | KR20030007399A (ja) |
TW (1) | TW541758B (ja) |
WO (1) | WO2002043459A1 (ja) |
Cited By (2)
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EP1585148A1 (en) * | 2002-12-27 | 2005-10-12 | TDK Corporation | Granular substance, magnetic thin film, and magnetic device |
RU2632985C2 (ru) * | 2016-02-16 | 2017-10-11 | Российская Федерация, От Имени Которой Выступает Министерство Промышленности И Торговли Российской Федерации | Радиопоглощающее покрытие |
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US6989792B2 (en) * | 2002-08-30 | 2006-01-24 | Auden Techno Corp. | Device for radio communication equipment to reduce electromagnetic energy absorbency of a human body |
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JP3876809B2 (ja) * | 2002-09-30 | 2007-02-07 | 住友電気工業株式会社 | 電磁波吸収体とその製造方法 |
JP2004162033A (ja) * | 2002-10-21 | 2004-06-10 | Jsr Corp | 電着用水性分散液、電磁波ノイズ吸収フィルムおよびインダクタ電子部品 |
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TWI678144B (zh) * | 2017-07-24 | 2019-11-21 | 理研股份有限公司 | 近場用雜訊抑制片 |
JP6461414B1 (ja) * | 2018-08-02 | 2019-01-30 | 加川 清二 | 電磁波吸収複合シート |
JP7200923B2 (ja) * | 2019-12-25 | 2023-01-10 | 株式会社オートネットワーク技術研究所 | 通信用電線 |
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JPH05179051A (ja) * | 1991-04-17 | 1993-07-20 | Hideo Oka | 磁性組成物 |
JPH10214717A (ja) * | 1997-01-30 | 1998-08-11 | Mitsui Chem Inc | 電磁波シールド |
JPH11177273A (ja) * | 1997-12-08 | 1999-07-02 | Nippon Paint Co Ltd | 電子機器筐体及び不要輻射波低減方法 |
US5938979A (en) * | 1997-10-31 | 1999-08-17 | Nanogram Corporation | Electromagnetic shielding |
JPH11269503A (ja) * | 1998-03-19 | 1999-10-05 | Hitachi Metals Ltd | Fe基ナノ結晶磁性粉末、およびその製造方法ならびに、これを用いた電波ノイズ抑制部材 |
JP2000307287A (ja) * | 1999-04-22 | 2000-11-02 | Tokin Corp | 電磁干渉抑制体 |
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DE19716882A1 (de) * | 1997-04-22 | 1998-10-29 | Basf Ag | Siliziumhaltige Eisenpulver |
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2000
- 2000-11-21 JP JP2000354254A patent/JP2002158484A/ja active Pending
-
2001
- 2001-11-16 KR KR1020027009313A patent/KR20030007399A/ko not_active Application Discontinuation
- 2001-11-16 WO PCT/JP2001/010058 patent/WO2002043459A1/ja not_active Application Discontinuation
- 2001-11-16 US US10/181,320 patent/US20030107025A1/en not_active Abandoned
- 2001-11-16 EP EP01982830A patent/EP1274293A1/en not_active Withdrawn
- 2001-11-20 TW TW090128746A patent/TW541758B/zh active
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
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JPH05179051A (ja) * | 1991-04-17 | 1993-07-20 | Hideo Oka | 磁性組成物 |
JPH10214717A (ja) * | 1997-01-30 | 1998-08-11 | Mitsui Chem Inc | 電磁波シールド |
US5938979A (en) * | 1997-10-31 | 1999-08-17 | Nanogram Corporation | Electromagnetic shielding |
JPH11177273A (ja) * | 1997-12-08 | 1999-07-02 | Nippon Paint Co Ltd | 電子機器筐体及び不要輻射波低減方法 |
JPH11269503A (ja) * | 1998-03-19 | 1999-10-05 | Hitachi Metals Ltd | Fe基ナノ結晶磁性粉末、およびその製造方法ならびに、これを用いた電波ノイズ抑制部材 |
JP2000307287A (ja) * | 1999-04-22 | 2000-11-02 | Tokin Corp | 電磁干渉抑制体 |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1585148A1 (en) * | 2002-12-27 | 2005-10-12 | TDK Corporation | Granular substance, magnetic thin film, and magnetic device |
EP1585148A4 (en) * | 2002-12-27 | 2008-04-02 | Tdk Corp | GRAIN SUBSTANCE, THIN MAGNETIC FILM AND MAGNETIC DEVICE |
RU2632985C2 (ru) * | 2016-02-16 | 2017-10-11 | Российская Федерация, От Имени Которой Выступает Министерство Промышленности И Торговли Российской Федерации | Радиопоглощающее покрытие |
Also Published As
Publication number | Publication date |
---|---|
TW541758B (en) | 2003-07-11 |
JP2002158484A (ja) | 2002-05-31 |
EP1274293A1 (en) | 2003-01-08 |
KR20030007399A (ko) | 2003-01-23 |
US20030107025A1 (en) | 2003-06-12 |
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