Composite material having low electromagnetic reflection and refraction

• US 20030002045A1
• Filed: 05/22/2002
• Published: 01/02/2003
• Est. Priority Date: 05/23/2001
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Smith, David R., Padilla, Willie J., Nemat-Nasser, Syrus C.
• Granted Patent: US 8,114,489 B2
• Time in Patent Office: Days
• US Class Current: 356/445
• CPC Class Codes: H01Q 1/42 Housings not intimately mechanically associated with radiating elements, e.g. radome
• CPC Class Codes: H01Q 1/425 comprising a metallic grid
• CPC Class Codes: H01Q 15/0006 Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices H01Q15/12, H01Q15/22, H01Q15/24 take precedence
• CPC Class Codes: H01Q 15/148 with means for varying the reflecting properties H01Q15/147 takes precedence
• CPC Class Codes: H01Q 3/44 varying the electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element
• CPC Class Codes: Y10T 428/13 Hollow or container type article [e.g., tube, vase, etc.]
• CPC Class Codes: Y10T 428/1303 Paper containing [e.g., paperboard, cardboard, fiberboard, etc.]
• CPC Class Codes: Y10T 428/1352 Polymer or resin containing [i.e., natural or synthetic]
• CPC Class Codes: Y10T 428/1359 Three or more layers [continuous layer]
• CPC Class Codes: Y10T 428/139 Open-ended, self-supporting conduit, cylinder, or tube-type article
• CPC Class Codes: Y10T 428/24 Structurally defined web or sheet [e.g., overall dimension, etc.]

Abstract

A composite material has a host dielectric with an artificial plasmon medium embedded in the host. The artificial plasmon medium has a dielectric function of less than 1, and a plasma frequency selected to result in the permittivity of the composite being substantially equal to 1.

Claims

1. A composite material comprising:

a host dielectric effective medium having an index of refraction greater than 1; and

an artificial plasmon medium embedded in said host medium, said artificial plasmon medium having a dielectric function less than 1, said artificial plasmon medium having a plasma frequency selected to result in the permittivity of the composite material being substantially equal to 1 for incident electromagnetic radiation of a desired frequency.

2. A composite material as defined by claim 1 wherein said artificial plasmon medium is selected and spatially arranged to result in the composite material having the permeability substantially equal to 1 for incident electromagnetic radiation of a desired frequency.

3. A composite material as defined by claim 1 wherein said artificial plasmon medium is selected and spatially arranged to result in the composite material having both the relative index-of-refraction and the relative impedance both substantially equal to 1.

4. A composite material as defined by claim 1 wherein said host dielectric medium has a dielectric constant ε

_host, said artificial plasmon medium has a plasma frequency f_p, and the composite material has an effective permittivity ε

_eff defined by;

ε

_eff=ε

_host−

(f_p/f)²

where f is the frequency of incident electromagnetic radiation.

5. A composite material as defined by claim 1 wherein said permittivity is expressed as:

ε

_eff=ε

E_host−

(f_p/f)² where f_p is said artificial plasmon medium plasma frequency, and f is said frequency of the incident electromagnetic radiation.

6. A composite material as defined by claim 1 wherein said artificial plasmon medium comprises a conductor.

7. A composite material as defined by claim 1 wherein said artificial plasmon medium comprises elongated metal elements spaced apart from one another by a distance d less than the wavelength of said incident electromagnetic radiation.

8. A composite material as defined by claim 1 wherein said artificial plasmon medium comprises metal wire.

9. A composite material as defined by claim 8 wherein said metal wire conductor is arranged as a lattice having a spacing d between lattice members, and has a plasma frequency defined by:

10. A composite material as defined by claim 9 wherein said metal wire conductor is selected and arranged to result in a plasma frequency substantially equal to said desired frequency.

11. A composite material as defined by claim 1 wherein said artificial plasmon medium comprises a material selected from the group consisting of aluminum, copper, gold, and silver.

12. A composite material as defined by claim 1 wherein said artificial plasmon medium comprises a plurality of regularly spaced portions.

13. A composite material as defined by claim 12 wherein said regularly spaced artificial plasmon medium portions are substantially planar with one another.

14. A composite material as defined by claim 12 wherein said plurality of regularly spaced portions may be organized into planes, each of said planes comprising a plurality of regularly spaced conductor portions planar with one another.

15. A composite material as defined by claim 14 wherein at least one of said plurality of artificial plasmon medium planes is substantially normal to at least a second of said plurality of artificial plasmon medium planes.

16. A composite material as defined by claim 12 wherein said artificial plasmon medium comprises a plurality of substantially straight lengths substantially parallel to one another.

17. A composite material as defined by claim 16 wherein each of said lengths having a plurality of inductive elements.

18. A composite material as defined by claim 12 wherein each of said lengths comprises a length of metal wire having a plurality of substantially regularly spaced turns.

19. A composite material as defined by claim 12 wherein said plurality of regularly spaced portions are spaced from one another by a distance that is not greater than a wavelength corresponding to the wavelength of the incident electromagnetic radiation.

20. A composite material as defined by claim 1 wherein said dielectric host comprises one or more members selected from the group consisting of:

thermoplastics, ceramics, oxides of metals, and mica.

21. A composite material as defined by claim 1 wherein said dielectric host comprises a three dimensional solid.

22. A composite material as defined by claim 1 wherein said dielectric host has substantially planar first and second surfaces, and wherein at least a portion of said artificial plasmon medium comprises a substantially planar shape substantially parallel to said dielectric host first and second surfaces.

23. A composite material as defined by claim 1 wherein said host dielectric effective medium has a general bowl shape.

24. A composite material as defined by claim 1 wherein said host dielectric effective medium comprises an enclosure for containing electronics.

25. A material as defined by claim 1 wherein said artificial plasmon medium comprises a material selected from the group of materials consisting of periodic arrangements of metal scattering elements, psuedo-periodic arrangements of metal scattering elements, and random arrangements of metal scattering elements.

26. A composite material comprising:

a host dielectric effective medium having an index of refraction greater than 1, said host dielectric effective medium comprising a three dimensional solid material; and

an artificial plasmon medium embedded in said host medium, said artificial plasmon medium having a dielectric function less than 1, said artificial plasmon medium having a plasma frequency selected to result in the permittivity and the permeability of the composite material being substantially equal to 1 for incident electromagnetic radiation of a desired frequency, said artificial plasmon medium comprising elongated metal elements spaced apart from one another by a distance less than the wavelength of said incident electromagnetic radiation.