Wave absorber and manufacturing method of wave absorber

• US 7,864,095 B2
• Filed: 02/25/2005
• Issued: 01/04/2011
• Est. Priority Date: 02/27/2004
• 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:
  US10/598,345
• Publication Number:
  US 20080212304A1
• Time in Patent Office: 2,139 Days
• Field of Search: 342 1- 4
• US Class Current: 342/1
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 1/44 using equipment having another main function to serve additionally as an antenna , e.g. means for giving an antenna an aesthetic aspectH01Q1/27 - H01Q1/34 take precedence
• CPC Class Codes: H01Q 15/00 Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices variable for purpose of altering directivity H01Q3/00; arrangements of such devices for guiding waves H01P3/20; variable for purpose of modulation H03C7/02
• 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 17/00 Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
• CPC Class Codes: H05K 9/0083 comprising electro-conductive non-fibrous particles embedded in an electrically insulating supporting structure, e.g. powder, flakes, whiskers H05K9/0086 takes precedence
• CPC Class Codes: H05K 9/0086 comprising a single discontinuous metallic layer on an electrically insulating supporting structure, e.g. metal grid, perforated metal foil, film, aggregated flakes, sintering
• CPC Class Codes: H05K 9/0088 comprising a plurality of shielding layers; combining different shielding material structure
• CPC Class Codes: Y10T 29/49126 Assembling bases

Abstract

The problem of the present invention is to offer a wave absorber that has reflection attenuation capability sufficient to enable prevention of communication disturbances due to reflection and the like of EM waves, that enables greater thinness and lighter weight, and that has wide-band attenuation properties, as well as a manufacturing method of the wave absorber. The wave absorber of the present invention has a structure which sequentially laminates a grid-like conductor layer composed of an electric conductor, a first dielectric layer, a high-resistance conductor layer having a surface resistivity within a prescribed range, a second dielectric layer, and a pattern layer having multiple patterns composed of an electric conductor, wherein each pattern in said pattern layer differs in either or both of size and form relative to another adjacent pattern.

Claims

1. A wave absorber comprising a structure which sequentially laminates a conduct layer which is composed of an electric conductor and reflects EM waves, a first dielectric layer composed of dielectric material in one layer or multiple layers, a high-resistance conductor layer which has a surface resistivity within a prescribed range and converts EM waves to heat, a second dielectric layer composed of dielectric material in one layer or multiple layers, and a pattern layer having multiple patterns composed of an electric conductor;

wherein

each pattern in said pattern layer differs in either or both of size and form relative to another adjacent pattern,

the conduct layer reflects EM waves passed through the pattern layer, the second dielectric layer, the high-resistance conductor layer and the first dielectric layer, a resistivity of the high-resistance conductor layer is larger than a resistivity of the conduct layer, and

a surface resistivity of the high-resistance conductor layer is in a range from 100 Ω

/□

to 100 kΩ

/□

.

2. The wave absorber according to claim 1, wherein the patterns in said pattern layer comprise loop patterns given a loop form;

said loop patterns comprise conductors with a shape having a line width value that is 5 percent to 25 percent relative to the center line length which is the length of the center line of the pertinent loop pattern;

the center line lengths of said loop patterns are lengths that are from 60 percent to 140 percent of the wavelength of the EM waves that are the object of absorption; and

any one loop pattern in said pattern layer and another loop pattern adjacent to the pertinent loop pattern differ in said center line lengths.

3. The wave absorber according to claim 1, wherein the center line lengths of said loop patterns are lengths that are from 60 percent to 140 percent of the wavelength of the EM waves that are the object of absorption;

and any one loop pattern in said pattern layer and another loop pattern adjacent to the pertinent loop pattern differ in form.

4. The wave absorber according to claim 1, wherein at least one of said loop patterns in said pattern layer has a form where a projecting form is provided on a portion of the lines in loop form.

5. The wave absorber according to claim 1, wherein the loop patterns in said pattern layer are such that an aggregate of multiple loop patterns of differing form or size constitutes one unit, and the space between the pertinent units is disposed at a prescribed interval.

6. The wave absorber according to claim 1, comprising a configuration where a protective layer is laminated onto at least one of the surface sides of said conduct layer and pattern layer.

7. The wave absorber according to claim 1, wherein the ratio of the thicknesses of said first dielectric layer and second dielectric layer is in a range from 0.1 to 10.

8. The wave absorber according to claim 1, wherein said conduct layer is a low-resistance conductor layer with a surface resistivity of 10 Ω

/□

or less.

9. The wave absorber according to claim 1, wherein said conduct layer is a grid-like conductor layer configured from a grid-like pattern.

10. The wave absorber according to claim 9, wherein said grid-like conductor layer has a line width of 100 μ

m or less, and a line center interval that is 1/16 or less of the wavelength of the EM waves that are the object of absorption.

11. The wave absorber according to claim 1, wherein the conductors used in said conduct layer, high-resistance conductor layer and pattern layer are composed of optically transparent conductive material, and said first and second dielectric layer and protective layer are composed of optically transparent dielectric material.

12. The wave absorber according to claim 1, wherein at least one layer among said high-resistance conductor layer, first dielectric layer and second dielectric layer is composed of dielectric material containing conductive oxide.

13. The wave absorber according to claim 12, wherein said conductive oxide is dielectric material containing ATO (antimony tin oxide).

14. The wave absorber according to claim 1, wherein at least one layer among said high-resistance conductor layer, first dielectric layer and second dielectric layer is composed of dielectric material containing conductive carbon powder.

15. The wave absorber according to claim 14, wherein at least one layer among said high-resistance conductor layer, first dielectric layer and second dielectric layer is composed of dielectric foam material containing conductive carbon powder.

16. The wave absorber according to claim 14, wherein only said high-resistance conductor layer is composed of dielectric material containing conductive carbon powder.

17. The wave absorber according to claim 14, wherein at least one layer among said high-resistance conductor layer, first dielectric layer and second dielectric layer is composed of dielectric material containing conductive carbon powder where carbon powder content differs among the pertinent high-resistance conductor layer, first dielectric layer and second dielectric layer.

18. The wave absorber according to claim 1, wherein the conduct layer and the high-resistance conductor layer are made of different materials from each other.

19. A wave absorber comprising at least a conduct layer which is composed of a conductor and reflects EM waves, a first dielectric layer composed of dielectric material in one layer or multiple layers, a linear pattern resistance layer which converts EM waves to heat and has linear patterns composed of a high-resistance conductor which is a conductor having a higher resistivity than said conduct layer, a second dielectric layer composed of dielectric material in one layer or multiple layers, and a pattern layer having multiple patterns composed of a conductor,

wherein the conduct layer reflects EM waves passed through the pattern layer, the second dielectric layer, the linear pattern resistance layer and the first dielectric layer, a resistivity of the linear pattern resistance layer is larger than a resistivity of the conduct layer, and

the high-resistance conductor of the linear pattern resistance layer has a volume resistivity of 1.0 E-4 Ω

cm or more and 1.0 E-1 Ω

cm or less.

20. The wave absorber according to claim 19, wherein said conduct layer, said first dielectric layer, said linear pattern resistance layer, said second dielectric layer, and said pattern layer are laminated in the pertinent order.

21. The wave absorber according to claim 19, wherein said conduct layer, said first dielectric layer, said pattern layer, said second dielectric layer, and said linear pattern resistance layer are laminated in the pertinent order.

22. The wave absorber according to claim 19, wherein the conduct layer and the linear pattern resistance layer are made of different materials from each other.

24. The wave absorber according to claim 19 or 23, wherein said linear pattern resistance layer is configured either by having linear patterns composed of a high-resistance conductor intersect, or by forming said linear patterns into a hexagonal honeycomb shape.

25. The wave absorber according to claim 19 or 23, wherein at least one among said conduct layer, pattern layer, linear pattern resistance layer and grid-like conductor layer has multiple linear patterns, where the line center interval which is the center interval of said linear patterns that are adjacent is 1/16 or less of the wavelength of the EM waves that are the object of absorption.

26. The wave absorber according to claim 25, wherein the line width which is the width of said linear pattern resistance layer is 100 μ

m or less.

27. The wave absorber according to claim 19 or 23, wherein each pattern of said pattern layer differs in at least one or the other of size and form relative to another adjacent pattern.

28. The wave absorber according to claim 19 or 23, wherein each pattern of said pattern layer is configured to have at least one or the other of a form that is any one of circular, rectangular, polygonal or a loop form having these forms as its external form, and a form that adds a projecting form to the pertinent one of these forms.

29. The wave absorber according to claim 19 or 23, which has a protective layer laminated onto at least one or the other of the front face and rear face of the laminate structure.

30. The wave absorber according to claim 19 or 23, wherein all of said component layers are made transparent or semi-transparent.

23. A wave absorber comprising a structure where at least a grid-like conductor layer which is formed into a grid by patterns composed of a conductor and reflects EM waves, a first dielectric layer composed of dielectric material in one layer or multiple layers, a linear pattern resistance layer which converts EM waves to heat and has linear patterns composed of a high-resistance conductor which is a conductor with a higher resistivity than the conductor that forms said grid-like conductor layer, a second dielectric layer composed of dielectric material in one layer or multiple layers, and a pattern layer having multiple patterns composed of a conductor are laminated in the pertinent order,

wherein the grid-like conductor layer reflects EM waves passed through the pattern layer, the second dielectric layer, the linear pattern resistance layer and the first dielectric layer,

a resistivity of the linear pattern resistance layer is larger than a resistivity of the grid-like conductor layer, and

the high-resistance conductor of the linear pattern resistance layer has a volume resistivity of 1.0 E-4 Ω

cm or more and 1.0 E-1 Ω

cm or less.

31. The wave absorber according to claim 23, wherein the grid-like conductor layer and the linear pattern resistance layer are made of different materials from each other.

32. A wave absorber manufacturing method comprising a process of laminating a radio wave reflection layer composed of a conductor that reflects EM waves, a first dielectric layer composed of dielectric material in one layer or multiple layers, a linear pattern resistance layer which converts EM waves to heat and has linear patterns composed of a high resistance conductor which is a conductor with a higher resistivity than said radio wave reflection layer, a second dielectric layer composed of dielectric material in one layer or multiple layers, and a pattern layer having multiple patterns composed of a conductor wherein the radio wave reflection layer reflects EM waves passed through the pattern layer, the second dielectric layer, the linear pattern resistance layer and the first dielectric layer, and the high-resistance conductor of the linear pattern resistance layer has a volume resistivity of 1.0 E-4 Ω

cm or more and 1.0 E-1 Ω

cm or less, and

a process of forming the linear patterns of said linear pattern resistance layer using the screen printing method.

33. The wave absorber manufacturing method according to claim 32, wherein the radio wave reflection layer and the linear pattern resistance layer are made of different materials from each other.

34. A wave absorber manufacturing method comprising a process of laminating a radio wave reflection layer composed of a conductor that reflects EM waves, a first dielectric layer composed of dielectric material in one layer or multiple layers, a linear pattern resistance layer which converts EM waves to heat and has linear patterns composed of a high-resistance conductor which is a conductor with a higher resistivity than said radio wave reflection layer, a second dielectric layer composed of dielectric material in one layer or multiple layers, and a pattern layer having multiple patterns composed of a conductor wherein the radio wave reflection layer reflects EM waves passed through the pattern layer, the second dielectric layer, the linear pattern resistance layer and the first dielectric layer, and the high-resistance conductor of the linear pattern resistance layer has a volume resistivity of 1.0 E-4 Ω

cm or more and 1.0 E-1 Ω

cm or less, and

a process of forming the linear patterns of said linear pattern resistance layer using the ink jet method.

35. The wave absorber manufacturing method according to claim 34, wherein the radio wave reflection layer and the linear pattern resistance layer are made of different materials from each other.

36. A wave absorber comprising at least:

a conduct layer which is composed of a conductor and reflects EM waves, a first dielectric layer composed of dielectric material in one layer or multiple layers, a planar resistance layer which is composed of dielectric material containing conductive powder and converts EM waves to heat, a second dielectric layer composed of dielectric material in one layer or multiple layers, and a pattern layer having multiple patterns composed of a conductor, wherein the conduct layer reflects EM waves passed through the pattern layer, the second dielectric layer, the planar resistance layer and the first dielectric layer,

a resistivity of the planar resistance layer is larger than a resistivity of the conduct layer, and

a surface resistivity of the planar resistance layer is in a range from 100 Ω

/□

to 100 kΩ

/□

.

37. The wave absorber according to claim 36, wherein said conduct layer, said first dielectric layer, said planar resistance layer, said second dielectric layer, and said pattern layer are laminated in the pertinent order.

38. The wave absorber according to claim 36, wherein said planar resistance layer is composed of material where glass cloth is impregnated with epoxy resin in which conductive powder such as carbon, silver, nickel or the like has been dispersed.

39. The wave absorber according to claim 36, wherein each pattern of said pattern layer differs at least in one or the other of size and form relative to another adjacent pattern.

40. The wave absorber according to claim 36, wherein each pattern of said pattern layer is configured to have at least one or the other of a form that is any one of circular, rectangular, polygonal or a loop form having these forms as its external form, and a form that adds a projecting form to the pertinent one of these forms.

41. The wave absorber according to claim 36, which has a protective layer laminated onto at least one or the other of the front face and rear face of the laminate structure.

42. A wave absorber manufacturing method comprising a process of laminating a conduct layer which is composed of a conductor and reflects EM waves, a first dielectric layer composed of dielectric material in one layer or multiple layers, a planar resistance layer which is composed of dielectric material containing conductive powder and converts EM waves to heat, a second dielectric layer composed of dielectric material in one layer or multiple layers, and a pattern layer having multiple patterns composed of a conductor, wherein the conduct layer reflects EM waves passed through the pattern layer, the second dielectric layer, the planar resistance layer and the first dielectric layer, a resistivity of the planar resistance layer is larger than a resistivity of the conduct layer;

and a surface resistivity of the planar resistance layer is in a range from 100 Ω

/□

to 100 kΩ

/□

, and

a process of forming a prepreg wherein, with respect to said planar resistance layer, said first dielectric layer and said second dielectric layer are bonded with interposition of the pertinent planar resistance layer.

43. The wave absorber manufacturing method according to claim 42, wherein said planar resistance layer is formed by using at least a process where glass cloth is impregnated with epoxy resin in which conductive powder such as carbon, silver and nickel has been dispersed.

44. A wave absorber comprising a structure wherein there is sequential lamination of at least a conduct layer which is composed of an electric conductor and reflects EM waves, a first dielectric layer composed of dielectric material in one layer or multiple layers, a high-resistance conductor layer which has a surface resistivity within a prescribed range and converts EM waves to heat, a second dielectric layer composed of dielectric material in one layer or multiple layers, and a pattern layer having multiple patterns composed of an electric conductor, and comprising a configuration wherein a protective layer which may be interposed as necessary is laminated onto at least one surface side of said conduct layer and pattern layer wherein

the conduct layer reflects EM waves passed through the pattern layer, the second dielectric layer, the high-resistance conductor layer and the first dielectric layer,

a resistivity of the high-resistance conductor layer is larger than a resistivity of the conduct layer, and

a surface resistivity of the high-resistance conductor layer is in a range from 100 Ω

/□

to 100 kΩ

/□

.

46. The wave absorber according to claim 44 or 45, wherein said high-resistance conductor layer is composed of conductive oxide material.

47. The wave absorber according to claim 46, wherein said high resistance conductor layer is composed of ITO (indium tin oxide), which is a conductive oxide material.

48. The wave absorber according to claim 44 or 45, wherein said high resistance conductor layer is composed of carbon material having conductivity.

45. A wave absorber comprising a structure wherein there is sequential lamination of a conduct layer which is composed of an electric conductor and reflects EM waves, a first dielectric layer composed of dielectric material in one layer or multiple layers, a high-resistance conductor layer which has a surface resistivity within a prescribed range and converts EM waves to heat, a second dielectric layer composed of dielectric material in one layer or multiple layers, and a pattern layer having multiple patterns composed of an electric conductor, and comprising a configuration wherein a protective layer which may be interposed as necessary is laminated onto at least one surface side of said conduct layer and pattern layer, wherein each pattern of said pattern layer differs in either or both of size and shape relative to another adjacent pattern, and

the conduct layer reflects EM waves passed through the pattern layer, the second dielectric layer, the high-resistance conductor layer and the first dielectric layer,

a resistivity of high-resistence conductor layer is larger than a resistivity of the conduct layer, and

a surface resistivity of the high-resistance conductor layer is in a range from 100 Ω

/□

to 100 kΩ

/□

.