ELECTRO-FERROMAGNETIC, TUNABLE ELECTROMAGNETIC BAND-GAP, AND BI-ANISOTROPIC COMPOSITE MEDIA USING WIRE CONFIGURATIONS

• US 20050146402A1
• Filed: 10/10/2003
• Published: 07/07/2005
• Est. Priority Date: 10/10/2002
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Inventors: Mosallaei, Hossein, Sarabandi, Kamal
• Granted Patent: US 6,933,812 B2
• Time in Patent Office: Days
• US Class Current: 333/219
• CPC Class Codes: H01P 1/2005 Electromagnetic photonic bandgaps [EPB], or photonic bandgaps [PBG]
• CPC Class Codes: H01P 3/08 Microstrips; Strip lines
• 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 15/006 Selective devices having photonic band gap materials or materials of which the material properties are frequency dependent, e.g. perforated substrates, high-impedance surfaces
• CPC Class Codes: H01Q 15/0086 said selective devices having materials with a synthesized negative refractive index, e.g. metamaterials or left-handed materials

Abstract

An artificial electro-ferromagnetic meta-material demonstrates the design of tunable band-gap and tunable bi-anisotropic materials. The medium is obtained using a composite mixture of dielectric, ferro-electric, and metallic materials arranged in a periodic fashion. By changing the intensity of an applied DC field the permeability of the artificial electro-ferromagnetic can be properly varied over a particular range of frequency. The structure shows excellent Electromagnetic Band-Gap (EBG) behavior with a band-gap frequency that can be tuned by changing the applied DC field intensity. The building block of the electro-ferromagnetic material is composed of miniaturized high Q resonant circuits embedded in a low-loss dielectric background. The resonant circuits are constructed from metallic loops terminated with a printed capacitor loaded with a ferro-electric material. Modifying the topology of the embedded-circuit, a bi-anisotropic material (tunable) is examined. The embedded-circuit meta-material is treated theoretically using a transmission line analogy of a medium supporting TEM waves.

Claims

1. An electro-ferromagnetic meta-material comprising:

a dielectric material; and

a plurality of embedded resonant circuits arranged in a periodic structure within the dielectric material, each of the plurality of embedded resonant circuits including a metal loop having an arbitrary shape and size with at least one capacitive gap, the plurality of embedded resonant circuits defining means for varying permeability of an electro-ferromagnetic meta-material with an external direct current electric field.

2. The meta-material of claim 1, wherein each of the plurality of embedded resonant circuits has an identical resonant frequency in a plane perpendicular to a propagation direction, while being capable of having different resonant frequencies along the direction of propagation.

3. The meta-material of claim 1, wherein the dielectric material is a homogeneous dielectric material.

4. The meta-material of claim 1, wherein by varying a gap between the embedded resonant circuits along a direction of electric field polarization an effective permittivity of the meta-material can be adjusted.

5. The meta-material of claim 1, wherein the loop comprises at least two capacitive gaps, each of the two capacitive gaps located on an opposite leg of the metal loop, and wherein at least one of the two capacitive gaps is filled by a ferro-electric material.

6. The meta-material of claim 5, wherein the electronic tunable capacitor is supplied by one of diode and ferro-electric varactors.

8. The meta-material of claim 1, wherein the plurality of embedded resonant circuits comprise a stack of periodically printed circuits on a substrate of dielectric material.

10. The meta-material of claim 1, wherein odd layers of the plurality of embedded resonant circuits have a first resonant frequency and even layers of the plurality of embedded resonant circuits have a second resonant frequency.

11. The meta-material of claim 10, wherein the loop comprises at least two capacitive gaps, each of the two capacitive gaps located on an opposite leg of the metal loop.

12. The meta-material of claim 1, wherein respective capacitive gaps of odd layers of the plurality of embedded resonant circuits have a first capacitive value and respective capacitive gaps of even layers of the plurality of embedded resonant circuits have a second capacitive value.

13. The meta-material of claim 1, wherein the plurality of embedded resonant circuits comprises a first layer of embedded resonant circuits, a second layer of embedded resonant circuits and a third layer of embedded resonant circuits;

and wherein each of the first layer, the second layer and the third layer has a unique resonant frequency.

14. The meta-material of claim 13 further comprising:

a plurality of I-shaped metallic strips located between adjacent embedded resonant circuits for increasing an effective permittivity of the dielectric material between the adjacent embedded resonant circuits.

19. The meta-material of claim 13, wherein a resonant frequency of the first layer is less than a resonant frequency of the second layer;

and wherein the resonant frequency of the second layer is less than a resonant frequency of the third layer.

20. The meta-material of claim 13, wherein each of the plurality of embedded resonant circuits further comprises a ferro-electric material filling the at least one capacitive gap.

21. The meta-material of claim 20, wherein the ferro-electric material comprises one of diode and ferro-electric varactors.

30. The meta-material of claim 19, wherein a wideband band-gap structure is provided.

31. The meta-material of claim 30, wherein the periodic structure comprises a three-dimensional cube.

32. The meta-material of claim 30, wherein the periodic structure comprises a three-dimensional structure having an isotropic band-gap independent of a wave incidence angle and a polarization state.

33. The meta-material of claim 1, wherein adjacent embedded resonant circuits are separated by a distance equivalent to a quarter wavelength.

7. An electro-ferromagnetic meta-material comprising:

a dielectric material;

a plurality of embedded resonant circuits arranged in a periodic structure within the dielectric material, each of the plurality of embedded resonant circuits including a metal loop having an arbitrary shape and size with at least one capacitive gap, wherein the loop includes at least two capacitive gaps each of the two capacitive gaps located on an opposite leg of the metal loop and wherein at least one of the two capacitive gaps includes an electronic tunable capacitor; and

a DC electric field applied to the dielectric material for tuning the electronic tunable capacitor to vary the band-gap of the meta-material.

9. (canceled)

15. An electro-ferromagnetic meta-material comprising:

a dielectric material;

a plurality of embedded resonant circuits arranged in a periodic structure within the dielectric material each of the plurality of embedded resonant circuits including a metal loop having an arbitrary shape and size with at least one capacitive gap, wherein the plurality of embedded resonant circuits includes a first layer of embedded resonant circuits a second layer of embedded resonant circuits and a third layer of embedded resonant circuits; and

wherein each of the first layers the second layer and the third layer has a unique resonant frequency, wherein adjacent embedded resonant circuits are separated by a distance equivalent to a quarter wavelength.

16. The meta-material of claim 15 further comprising:

a plurality of I-shaped metallic strips located between the adjacent embedded resonant circuits for increasing an effective permittivity of the dielectric material between the adjacent embedded resonant circuits.

17. The meta-material of claim 16, wherein a resonant frequency of the first layer is less than a resonant frequency of the second layer;

and wherein the resonant frequency of the second layer is less than a resonant frequency of the third layer.

18. The meta-material of claim 17, wherein the periodic structure comprises a three-dimensional cube.

22. The meta-material of claim 29, wherein the periodic structure comprises a three-dimensional cube.

23. The meta-material of claim 29, wherein the periodic structure comprises a three-dimensional structure having an isotropic band-gap independent of a wave incidence angle and a polarization state.

29. The meta-material of claim 15, wherein a wideband band-gap structure is provided.

24. An electro-ferromagnetic meta-material comprising:

a dielectric material; and

a plurality of embedded resonant circuits arranged in a periodic structure within the dielectric material, each of the plurality of embedded resonant circuits including a metal loop having an arbitrary shape and size with at least one capacitive gap, wherein the metal loop has a shape providing bi-anisotropic properties to the meta-material.

25. The meta-material of claim 24, wherein each of the plurality of embedded resonant circuits further comprises a ferro-electric material filling the at least one capacitive gap.

26. The meta-material of claim 24, wherein the at least one capacitive gap comprises two capacitive gaps, each of the two capacitive gaps located on an opposite leg of the metal loop, and wherein at least one of the two capacitive gaps includes an electronic tunable capacitor.

27. The meta-material of claim 26, wherein the electronic tunable capacitor is supplied by one of diode and ferro-electric varactors.

28. An electro-ferromagnetic meta-material comprising:

a dielectric material; and

a plurality of embedded resonant circuits arranged in a periodic structure within the dielectric material, each of the plurality of embedded resonant circuits including a metal loop having an arbitrary shape and size with at least one capacitive gap, wherein the capacitive gap is oriented generally perpendicular to the electric field for optimal performance.