EP0090432A2
Expired / Lapsed
EP
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Electro-magnetic wave absorbing material
Assignee: NEC Corp
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Filing: 1983-03-31
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Granted: —
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Expires: 2003-03-31
Abstract
Abstract An electro-magnetic wave absorbing member comprises a mixture of short fibers (2) of metal or alloy having a high electro-conductivity, a length of 0.1 mm to 50 mm and a length to diameter ratio larger than 10, ferrite and a high molecular weight synthetic resin. In a modification a sheet of this material is used as a low input impedance layer (13) and laminated with an electro-conductive sheet (12) and an impedance conversion layer (14). The member according to this invention can increase electrical loss contributing to the absorption of electro- magnetive waves, can stably control the absorption and can be used in many applications.
Inventors
- 👤 Kenichi Hatakeyama
- 👤 Tetsuji Inui
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 03:16
CPC Classifications
H; H05; H05K; H05K9/00; H05K9/0073; H05K9/0081; H05K9/009; C; C08; C08K; C08K3/00; C08K3/02; C08K3/08; C08K7/00; C08K7/02; C08K7/04; C08K7/06; F; F41; F41H; F41H3/00
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
48 words
An electro-magnetic wave absorbing material characterized by a mixture of short fibers (2) of metal or alloy having a high electric conductivity, a length of 0.1 mm to 50 mm and a length to diameter ratio larger than 10, a ferromagnetic material and a high molecular synthetic resin.
Claim 2
Dependent Claim
48 words
An electro-magnetic wave absorbing material characterized by a mixture of short fibers (2) of metal or alloy having a high electric conductivity, a length of 0.1 mm to 50 mm and a length to diameter ratio larger than 10, a ferromagnetic material and a high molecular synthetic resin.
Claim 3
Dependent Claim
24 words
The electro-magnetic wave absorbing material according to claim 1 wherein said material contains more than 3 % by weight of the short fibers (2).
Claim 4
Dependent Claim
33 words
The electro-magnetic wave absorbing material according to claim 1 or 2, wherein the metal or alloy is selected from the group consisting of Au, Ag, Cu, Al, Zn, Ni, Fe and alloys thereof.
Claim 5
Dependent Claim
29 words
The electro-magnetic wave absorbing material according to any of claims 1 to 3, wherein the ferromagnetic material is selected from the group consisting of ferrite, iron, cobalt and nickel.
Claim 6
Dependent Claim
18 words
The electro-magnetic wave absorbing material according to any of claims 1 to 4 which further comprises carbon black.
Claim 7
Dependent Claim
19 words
The electro-magnetic wave absorbing material according to any of claims 1 to 5, which further comprises a ferrodielectric substance.
Claim 8
Dependent Claim
31 words
The electro-magnetic wave absorbing material according to claim 6, wherein the ferrodielectric substance is selected from the group consisting of barium titanate, lead titanate, strontium titanate, lead neobate and lead zirconate.
Claim 9
Dependent Claim
81 words
An electro-magnetic wave absorbing body characterized by a low input impedance layer (13) formed on a electro-conductive member (12), and an impedance transforming layer (14) formed on the low input impedance layer (13), the low input impedance layer (13) comprising a mixture of short fibers (2) of metal or alloy having a high electric conductivity, a length of 0.1 mm to 50 mm and a length to diameter ratio larger than 10, a ferromagnetic material and a high molecular synthetic resin.
Claim 10
Dependent Claim
81 words
An electro-magnetic wave absorbing body characterized by a low input impedance layer (13) formed on a electro-conductive member (12), and an impedance transforming layer (14) formed on the low input impedance layer (13), the low input impedance layer (13) comprising a mixture of short fibers (2) of metal or alloy having a high electric conductivity, a length of 0.1 mm to 50 mm and a length to diameter ratio larger than 10, a ferromagnetic material and a high molecular synthetic resin.
Claim 11
Dependent Claim
23 words
The electro-magnetic wave absorbing body according to claim 8 wherein the impedance transforming layer (13) is made of a high molecular synthetic resin.
Claim 12
Dependent Claim
48 words
The electro-magnetic wave absorbing body according to claim 8 or 9 wherein the impedance transforming layer comprises a mixture of a high molecular synthetic resin and either one or both of a magnetic material and an electro-conductive material each in the form of particles, foils and short fibers.
Claim 13
Dependent Claim
30 words
The electro-magnetic wave absorbing member according to claim 10 wherein the magnetic material comprises a ferromagnetic material selected from the group consisting of ferrite, iron, cobalt, nickel and mixtures thereof.
Claim 14
Dependent Claim
27 words
The electro-magnetic wave absorbing body according to claim 10 or 11 wherein the electro-conductive material comprises at least one of electro-conductive metals, alloys of metals and carbon.
References Cited (Backward Citations)
No citation records indexed.
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