Multi-component electromagnetic wave absorption panels

• US 6,037,046 A
• Filed: 01/13/1997
• Issued: 03/14/2000
• Est. Priority Date: 01/13/1997
• Status: Expired due to Fees

• Current Assignee: Fujita Corporation (Daiwa House Industry Company Limited), Symetrix Corporation
• Original Assignee: Fujita Corporation (Daiwa House Industry Company Limited), Symetrix Corporation
• Inventors: Kimura, Kenichi, Kiyokawa, Hiroshi, Paz de Araujo, Carlos A., Joshi, Vikram
• Primary Examiner(s): YAMNITZKY, MARIE ROSE
• Application Number:
  US08/782,934
• Time in Patent Office: 1,156 Days
• Field of Search: 174/35 R, 174/36, 174/35 MS, 428/77, 428/49, 428/192, 428/195, 428/213, 428/220, 428/421, 428/422, 428/457, 428/463, 428/212, 428/323, 428/325, 428/412, 428/702, 106/290, 106/304, 106/308 M, 343/872, 343/873, 342/1, 342/4, 342/3, 342/2, 252/62.9, 252/62.54
• US Class Current: 428/212
• CPC Class Codes: E04B 1/92 Protection against other undesired influences or dangers buildings providing protection against external dangers E04H9/00; shielding against dangerous radiation G21F
• 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 17/004 using non-directional dissipative particles, e.g. ferrite powders H01Q17/005 takes precedence; flake-like H01Q17/002
• CPC Class Codes: H01Q 17/007 with means for controlling the absorption
• CPC Class Codes: H01Q 17/008 with a particular shape H01Q17/007 takes precedence
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/252 Glass or ceramic [i.e., fired or glazed clay, cement, etc.] [porcelain, quartz, etc.]
• CPC Class Codes: Y10T 428/31507 Of polycarbonate
• CPC Class Codes: Y10T 428/31544 Addition polymer is perhalogenated
• CPC Class Codes: Y10T 428/31678 Of metal

Abstract

An electromagnetic wave absorption panel for use in building construction includes a protective tile layer, an absorber layer, a metal reflective layer, and a building support layer, such as concrete. The absorber layer is multi-component structure, such as: a high dielectric constant layer and ferrite layer; a ferrite layer and a low dielectric constant layer; a ferrite and a polymer; a polymer and a material having a higher dielectric constant than the polymer; a ferroelectric, a ferrite, and a polymer; a ferrite, a polymer, and a high dielectric constant material; and a high dielectric constant material, a material in which the imaginary part of the permeability is greater than or equal to the real part of the permeability, and a low dielectric constant material. The invention also includes combinations of the above, such as: a high dielectric constant material, a ferrite, and a low dielectric constant material; and multiple layers of a ferrite and a polymer. The invention further includes the above structures and combinations with specific materials, such as a ferrite, a polymer, LSM, and a high dielectric constant material; and a ferrite, a polymer, and BST. The invention also includes: a multi-component absorber element having an effective real part of the permitivity, ε'"'"'_eff, and an effective real part of the permeability, μ'"'"'_eff, such that (ε'"'"'_eff μ'"'"'_eff)^1/2 ˜1/f over said range of frequencies, where f is the frequency of the incident wave; and a multi-component absorber element having an effective real part of the permitivity, ε'"'"'_eff, that decreases with frequency.

Claims

1. An electromagnetic wave absorption panel for absorbing waves incident on said panel at a point of incidence, said panel comprising:

a building support element;

a reflective element supported by said support element; and

a plurality of absorber elements supported by said support element, said absorber elements located closer to said point of incidence of said electromagnetic wave on said panel than said reflective element, said absorber elements stacked in a direction perpendicular to said reflective element and all of said absorber elements being on the same side of said reflective element with respect to said point of incidence, and each of said absorber elements comprising a first layer comprising a ferrite and a second layer comprising a low dielectric constant material, said second layer being different from said first layer in composition and at least one physical property that can affect an electromagnetic wave, and in each of said absorber elements said second layer located farther from said point of incidence of said electromagnetic wave than said first layer.

2. An electromagnetic wave absorption panel as in claim 1 wherein there are n of said absorber elements, where n is an integer between 2 and 100.

3. An electromagnetic wave absorption panel as in claim 1 wherein said low dielectric constant material comprises a polymer.

4. An electromagnetic wave absorption panel as in claim 1 wherein said ferrite comprises Ni₀.4 Zn₀.6 Fe₂ O₄.

5. An electromagnetic wave absorption panel for absorbing waves incident on said panel at a point of incidence, said panel comprising:

a building support element;

a reflective element supported by said support element; and

an absorber element supported by said support element, said absorber element located closer to said point of incidence of said electromagnetic wave on said panel than said reflective element, said absorber element comprising a first layer comprising a ferrite, a second layer comprising a low dielectric constant material, and a third layer comprising a high dielectric constant material, said first, second, and third layers all being on the same side of said reflective element with respect to said point of incidence, said second layer being different from said first layer in composition and at least one physical property that can affect an electromagnetic wave, said third layer being different from said first layer and said second layer in composition and at least one physical property that can affect an electromagnetic wave, and said second layer located farther from said point of incidence of said electromagnetic wave than said first layer.

6. An electromagnetic wave absorption panel as in claim 5 wherein said third layer is located closer to said point of incidence than said first layer.

7. An electromagnetic wave absorption panel as in claim 6 wherein said ferrite comprises Ni₀.4 Zn₀.6 Fe₂ O₄ and said low dielectric constant material comprises a polymer.

8. An electromagnetic wave absorption panel as in claim 6 wherein said high dielectric constant material comprises a 50/50 solid solution of BaTiO₃ and BaO.6Fe₂ O₃, said ferrite comprises Ni₀.4 Zn₀.6 Fe₂ O₄, and said low dielectric constant material comprises polytetrafluoroethylene.

9. An electromagnetic wave absorption panel as in claim 6 wherein said ferrite comprises Ni₀.4 Zn₀.6 Fe₂ O₄, said low dielectric constant material comprises polycarbonate, and said high dielectric constant material comprises Ba₀.7 Sr₀.3 TiO₃.

10. An electromagnetic wave absorption panel as in claim 6 wherein said ferrite comprises Ni₀.4 Zn₀.6 Fe₂ O₄ and said low dielectric constant material comprises polycarbonate.

11. An electromagnetic wave absorption panel as in claim 5 wherein said high dielectric constant material comprises a material selected from the group consisting of layered superlattice materials, ABO₃ -type perovskites, signet magnetics, and Z×

BaTiO₃ +(100%-Z)×

BiFeO₃ where 100%>

Z>

0%.

12. An electromagnetic wave absorption panel as in claim 11 wherein said high dielectric constant material comprises BST having the formula Ba₀.7 Sr₀.3 TiO₃.

13. An electromagnetic wave absorption panel as in claim 5 wherein said third layer is located farther from said point of incidence than said second layer.

14. An electromagnetic wave absorption panel as in claim 13 wherein said high dielectric constant material comprises a material selected from the group consisting of layered superlattice materials, ABO₃ -type perovskites, signet magnetics, and Z×

BaTiO₃ +(100%-Z)×

BiFeO₃ where 100%>

Z>

0%.

15. An electromagnetic wave absorption panel as in claim 14 wherein said high dielectric constant material comprises BST having the formula Ba₀.7 Sr₀.3 TiO₃.

16. An electromagnetic wave absorption panel as in claim 13 wherein said ferrite comprises Ni₀.4 Zn₀.6 Fe₂ O₄ and said low dielectric constant material comprises a polymer.

17. An electromagnetic wave absorption panel as in claim 13 wherein said ferrite comprises Ni₀.4 Zn₀.6 Fe₂ O₄, said low dielectric constant material comprises polycarbonate, and said high dielectric constant material comprises Ba₀.7 Sr₀.3 TiO₃.

18. An electromagnetic wave absorption panel as in claim 13 wherein said ferrite comprises Ni₀.4 Zn₀.6 Fe₂ O₄ and said low dielectric constant material comprises polycarbonate.

19. An electromagnetic wave absorption panel as in claim 13 wherein said high dielectric constant material comprises a 50/50 solid solution of BaTiO₃ and BaO.6Fe₂ O₃, said ferrite comprises Ni₀.4 Zn₀.6 Fe₂ O₄, and said low dielectric constant material comprises polytetrafluoroethylene.