Wave absorber

• US 7,777,664 B2
• Filed: 08/31/2005
• Issued: 08/17/2010
• Est. Priority Date: 09/06/2004
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Gas Chemical Company Incorporated (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Gas Chemical Company Incorporated (Mitsubishi Electric Corporation)
• Inventors: Nakano, Hisamatsu, Otani, Noboru, Masuda, Yoshiyuki
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Brainard; Timothy A
• Application Number:
  US11/574,701
• Publication Number:
  US 20070247349A1
• Time in Patent Office: 1,812 Days
• Field of Search: 342/1
• US Class Current: 342/1
• CPC Class Codes: H01Q 15/0013 said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective
• CPC Class Codes: H01Q 15/0026 said selective devices having a stacked geometry or having multiple layers
• CPC Class Codes: H01Q 15/14 Reflecting surfaces; Equivalent structures electromagnetic shields H01Q1/526
• CPC Class Codes: H01Q 17/00 Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
• CPC Class Codes: H01Q 19/10 using reflecting surfaces
• CPC Class Codes: H05K 9/0088 comprising a plurality of shielding layers; combining different shielding material structure

Abstract

A wave absorber of the present invention includes a sequentially laminated structure including an conductor layer (11) made of a conductive material; a first dielectric layer (polycarbonate substrate (12) and bismaleimide-triazine substrate (13)) made of one layer or a multilayer of a dielectric material; and a patterned layer (14) including a plurality of a pattern made of the conductive material, wherein the conductor layer, the first dielectric layer, and the patterned layer are laminated sequentially, and each pattern in the patterned layer (14) is different from other adjacent patterns with respect to at least one of size and shape. Therefore, the wave absorber has sufficient reflection-attenuating capability to prevent communication failure caused by a reflection of a radio wave and so on, can be thin-sized and reduced in weight, and has a wide-band attenuation property.

Claims

1. A wave absorber comprising:

a sequentially laminated structure comprising

a conductor layer formed of a conductive material;

a first dielectric layer formed of one layer or a multilayer of a dielectric material; and

a patterned layer including a plurality of patterns formed of the conductive material, wherein

the pattern in the patterned layer is a loop pattern having a loop shape or a patch pattern having a round shape or a square shape,

each of the patterns in the patterned layer is different from other adjacent patterns with respect to at least one of size and shape, and

a surface resistivity of the conductive material forming the pattern is within 5 Ω

/square to 30 Ω

/square.

2. A wave absorber according to claim 1, wherein

the pattern in the patterned layer is a loop pattern having a loop shape,

the loop pattern is formed of the conductive material having a shape in which a line width is within 5% to 25% of a central line length which is the length of the central line of the loop pattern,

the central line length of the loop pattern is within 60% to 140% of a wavelength of a radio wave to be absorbed, and

any one of the loop patterns in the patterned layer is different from other adjacent loop patterns to the loop pattern with respect to the central line length and shape.

3. A wave absorber according to claim 1, wherein at least one of the loop patterns and the patch patterns having the round shape or the square shape in the patterned layer has a shape in which a projection is added to a part of the pattern.

4. A wave absorber according to claim 1, wherein an assembly of a plurality of the loop patterns and/or the patch patterns whose shape or size is different to each other constitutes a unit, and the units are allocated such that a spacing between the units is predetermined.

5. A wave absorber according to claim 1, further comprising a second dielectric layer which is laminated on the surface of at least one of the conductor layer and the patterned layer.

6. A wave absorber according to claim 5, wherein

the conductive material used in the conductor layer and the patterned layer is optically transparent, and

the first and second dielectric layers are formed of an optically transparent conductive material.

7. A wave absorber according to claim 5, wherein

the conductor layer is a grating-shaped conductor layer having a grating-shaped pattern,

the conductive material used in the patterned layer is optically transparent, and

the first and second dielectric layers are formed of an optically transparent conductive material.

8. A wave absorber according to claim 1, wherein the conductor layer is a low-resistance conductor layer with a surface resistivity of 30 Ω

/square [Ω

/□

]or less.

9. A wave absorber according to claim 1, wherein the conductor layer is a grating-shaped conductor layer having a grating-shaped pattern.

10. A wave absorber according to claim 9, wherein the grating-shaped conductor layer has a line width of 100 μ

m or less and a central line spacing of one sixteen of a wavelength of an electromagnetic wave to be absorbed.