Electromagnetic Wave Absorber

• US 20080084259A1
• Filed: 03/01/2004
• Published: 04/10/2008
• Est. Priority Date: 03/01/2004
• Status: Active Grant

• Current Assignee: Nitta Corporation
• Original Assignee: Nitta Corporation
• Inventors: Go, Haruhide, Maenaka, Mamoru, Maezawa, Makoto, Sato, Shinichi, Yoshida, Takahiko, Kiyohara, Yoshiharu
• Granted Patent: US 7,804,439 B2
• Time in Patent Office: Days
• US Class Current: 333/243
• CPC Class Codes: H01Q 17/002 using short elongated elements as dissipative material, e.g. metallic threads or flake-like particles
• CPC Class Codes: H05K 9/0003 Shielded walls, floors, ceilings, e.g. wallpaper, wall panel, electro-conductive plaster, concrete, cement, mortar

Abstract

A thin, light and soft electromagnetic wave absorber is disclosed exhibiting an excellent workability. The first conductor element group of a first conductor element layer consists of aligned cross conductor elements and square conductor elements in regions surrounded by cross conductor elements. A radio wave incident from the first conductor element layer side is received by each element, internally subjected to multiple reflection and then absorbed by a first loss material layer. Since the first conductor element group is realized by the cross conductor elements and the square conductor elements, receiving effect is enhanced and the radio wave can be collected with a high collection efficiency.

Claims

1. An electromagnetic wave absorber, comprising:

element receiving means provided with a plurality of conductor elements having predetermined resonant frequencies and including a plurality of types of conductor elements that perform different receiving operations, the plurality of conductor elements being arranged spaced away from each other in a direction intersecting an incoming direction of electromagnetic waves, and the plurality of conductor elements being substantially polygonal and having at least one corner portion of an arc shape having a curvature radius corresponding to the resonant frequencies; and

a loss material for causing energy loss to electromagnetic waves, provided close to the element receiving means.

2. The electromagnetic wave absorber of claim 1, wherein the conductor elements are arranged also in the incoming direction of electromagnetic waves, in addition to the direction intersecting the incoming direction of electromagnetic waves.

3. The electromagnetic wave absorber of claim 1, further comprising electromagnetic wave reflecting means for reflecting electromagnetic waves, disposed on a side opposite to a side from which electromagnetic waves income with respect to the element receiving means.

4. The electromagnetic wave absorber of claim 1, wherein a conductivity of the conductor elements is at least 10,000 S/m.

5. The electromagnetic wave absorber of claim 1, wherein the conductor elements are made of metal.

6. The electromagnetic wave absorber of claim 1, wherein the electromagnetic wave absorber is formed in the shape of a sheet having a thickness of at least 0.1 mm and at most 4 mm.

7. The electromagnetic wave absorber of claim 1, wherein the electromagnetic wave absorber is formed in the shape of a sheet having a mass per unit area of at least 0.2 kg/m² and at most 5 kg/m².

8. The electromagnetic wave absorber of claim 1, wherein among the plurality of types of the conductor elements, one type of the conductor elements are cross conductor elements that are formed in the shape of crosses, and another type of the conductor elements are quadrangular conductor elements that are formed in the shape of planes,

the cross conductor elements and the quadrangular conductor elements are arranged in the direction intersecting the incoming direction of electromagnetic waves,

the cross conductor elements are arranged in a regular manner in the direction intersecting the incoming direction of electromagnetic waves, and

the quadrangular conductor elements are arranged in areas surrounded by the cross conductor elements so as to fill in the areas.

9. The electromagnetic wave absorber of claim 8, wherein the cross conductor elements are arranged such that radially extending portions are faced with each other, and the quadrangular elements are formed in the shape corresponding to the areas surrounded by the cross conductor elements.

10. The electromagnetic wave absorber of claim 1, wherein a size of a spacing between the conductor elements is determined so as to lower the resonant frequencies of the conductor elements.

12. The electromagnetic wave absorber of claim 1, wherein a property value of the loss material is determined based on the resonant frequencies of the conductor elements so as to improve the absorption efficiency of electromagnetic waves with the same frequency as the resonant frequencies.

13. The electromagnetic wave absorber of claim 1, wherein the electromagnetic wave absorber is made flame resistant, quasi-incombustibile, or incombustibile.

14. A method for absorbing electromagnetic waves by using the electromagnetic wave absorber of claim 1.

15. The electromagnetic wave absorber of claim 2, further comprising electromagnetic wave reflecting means for reflecting electromagnetic waves, disposed on a side opposite to a side from which electromagnetic waves income with respect to the element receiving means.

16. The electromagnetic wave absorber of claim 2, wherein a conductivity of the conductor elements is at least 10,000 S/m.

17. The electromagnetic wave absorber of claim 2, wherein among the plurality of types of the conductor elements, one type of the conductor elements are cross conductor elements that are formed in the shape of crosses, and another type of the conductor elements are quadrangular conductor elements that are formed in the shape of planes,

the cross conductor elements and the quadrangular conductor elements are arranged in the direction intersecting the incoming direction of electromagnetic waves,

the cross conductor elements are arranged in regular manner in the direction intersecting the incoming direction of electromagnetic waves, and

the quadrangular conductor elements are arranged in areas surrounded by the cross conductor elements so as to fill in the areas.

18. The electromagnetic wave absorber of claim 2, wherein a property value of the loss material is determined based on the resonant frequencies of the conductor elements so as to improve the absorption efficiency of electromagnetic waves with the same frequency as the resonant frequencies.

19. The electromagnetic wave absorber of claim 2, wherein the electromagnetic wave absorber is made flame resistant, quasi-incombustibile, or incombustibile.

20. A method for absorbing electromagnetic waves by using the electromagnetic wave absorber of claim 2.

11. (canceled)