Patent US4728554A successfully refreshed from Google Patents.
US4728554A
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Fiber structure and method for obtaining tuned response to high frequency electromagnetic radiation
Assignee: CNA Holdings LLC
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Filing: 1986-05-05
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Granted: 1988-03-01
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Expires: 2006-05-05
Abstract
Abstract The present invention relates to fiber structures and methods for obtaining tuned response to high frequency electromagnetic radiation, particularly at microwave frequencies. In one embodiment, a woven fabric is prepared with ferrite filled fibers oriented perpendicular to dielectric filled fibers. The fill of the fibers is selected to reflect radiation having a known frequency and polarization. In other embodiments, tuned structures are provided by disposing sheets containing oriented ferrite and dielectric fibers parallel to one another and moving the layers relative to one another to achieve the desired impedance for incident radiation.
Inventors
- 👤 Harris A. Goldberg
- 👤 Y. M. Faruq Marikar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 07:53
CPC Classifications
H; H01; H01Q; H01Q15/00; H01Q15/24; H01Q17/00; H01Q17/005; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24058; Y10T428/24124; Y10T428/25; Y10T428/256; Y10T428/257
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
98 words
A flexible woven fabric having reduced reflectivity to incident, linearly polarized electromagnetic radiation, said fabric comprising: first fibers comprising a polymer and from 20 to 80 volume percent particulate ferrite fill, said first fibers being oriented generally parallel to one another and generally aligned with the magnetic field of said incident polarized electromagnetic radiation; and second, non-magnetic dielectric fibers at least partially comprising a polymer, said second fibers being woven in said fabric so that said second fibers are oriented generally parallel to one another and generally aligned with the electric field of said incident polarized electromagnetic radiation.
Claim 2
Dependent Claim
98 words
A flexible woven fabric having reduced reflectivity to incident, linearly polarized electromagnetic radiation, said fabric comprising: first fibers comprising a polymer and from 20 to 80 volume percent particulate ferrite fill, said first fibers being oriented generally parallel to one another and generally aligned with the magnetic field of said incident polarized electromagnetic radiation; and second, non-magnetic dielectric fibers at least partially comprising a polymer, said second fibers being woven in said fabric so that said second fibers are oriented generally parallel to one another and generally aligned with the electric field of said incident polarized electromagnetic radiation.
Claim 3
Dependent Claim
24 words
The fabric of claim 1 wherein said first fibers comprise less than 70 volume percent polymer and greater than 30 volume percent ferrite fill.
Claim 4
Dependent Claim
20 words
The fabric of claim 2 wherein the polymer is selected from the group consisting of polyvinyl alcohol, polybenzimidazole and polyacrylonitrile.
Claim 5
Dependent Claim
38 words
The fabric of claim 1 wherein the ferrite fill is spinel particulates, said spinel particulates corresponding to the formula MFe.sub.2 O.sub.4 wherein M is manganese, iron, cobalt, nickel, copper, zinc, cadmium, magnesium, barium, strontium, or any combination thereof.
Claim 6
Dependent Claim
31 words
The fabric of claim 1 wherein the quantity and fill of said fibers are selected so that the fabric is a turned absorber of microwaves of a selected frequency and polarization.
Claim 7
Dependent Claim
29 words
The fabric of claim 1 wherein the quantity and fill of said fibers are selected so that the fabric is a tuned polarizer of microwaves reflected by the fabric.
Claim 8
Dependent Claim
31 words
The fabric of claim 1 wherein the quantity and fill of said fibers are selected so that the fabric is a tuned filter of microwaves of a selected frequency and polarization.
Claim 9
Dependent Claim
88 words
A tunable absorber for microwaves comprising: a first layer including ferrite fibers oriented generally parallel to one another; and a second layer overlying said first layer including dielectric fibers oriented generally parallel to one another, said second layer being orientable with respect to said first layer to change the angle between the ferrite fibers and the dielectric fibers to impedance match the absorber to a propagation medium from which the microwaves emanate; wherein the wavelength of the microwaves is much greater than the combined thickness of the layers.
Claim 10
Dependent Claim
88 words
A tunable absorber for microwaves comprising: a first layer including ferrite fibers oriented generally parallel to one another; and a second layer overlying said first layer including dielectric fibers oriented generally parallel to one another, said second layer being orientable with respect to said first layer to change the angle between the ferrite fibers and the dielectric fibers to impedance match the absorber to a propagation medium from which the microwaves emanate; wherein the wavelength of the microwaves is much greater than the combined thickness of the layers.
Claim 11
Dependent Claim
19 words
The tunable absorber of claim 8 wherein the frequency of said microwaves is from 300 MHz to 10 GHz.
Claim 12
Dependent Claim
14 words
The tunable absorber of claim 9 wherein the orientations of the layers are adjustable.
Claim 13
Dependent Claim
29 words
The tunable absorber of claim 10 wherein the ferrite fibers comprise a polymer and a ferrite fill and wherein the dielectric fibers comprise a polymer and a dielectric fill.
Claim 14
Dependent Claim
29 words
The tunable absorber of claim 11 wherein the amount of ferrite fill in the fibers is selected to minimize the demagnetization field along the length of the ferrite fibers.
Claim 15
Dependent Claim
31 words
The tunable absorber of claim 12 wherein the composition and concentration of the ferrite fill in the fibers is selected to provide impedance matching in a selected range of microwave frequencies.
Claim 16
Dependent Claim
31 words
The tunable absorber of claim 11 wherein the composition and concentration of dielectric fill in the fibers is selected to minimize the depolarization field along the length of the dielectric fibers.
Claim 17
Dependent Claim
37 words
The tunable absorber of claim 8 wherein the first layer is a composite film including the ferrite fibers and a binder, and wherein the second layer is a composite film including the dielectric fibers and a binder.
Claim 18
Dependent Claim
24 words
The tunable absorber of claim 15 wherein a dimension of a principal plane of said films is larger than one wavelength of the microwave.
Claim 19
Independent Claim
67 words
A method for impedance matching an object to a medium of propagation of incident microwave energy comprising: disposing at least one layer containing parallelized ferrite fibers on a surface of the object; disposing at least one layer containing parallelized dielectric fibers on the surface of the object; and moving the layers relative to one another to adjust an angle between said ferrite fibers and said dielectric fibers.
Claim 20
Independent Claim
67 words
A method for impedance matching an object to a medium of propagation of incident microwave energy comprising: disposing at least one layer containing parallelized ferrite fibers on a surface of the object; disposing at least one layer containing parallelized dielectric fibers on the surface of the object; and moving the layers relative to one another to adjust an angle between said ferrite fibers and said dielectric fibers.
Claim 21
Dependent Claim
85 words
An adjustable polarizing filter comprising: a first sheet containing oriented, ferrite particulate filled fibers, said ferrite filled fibers having a magnetic permeability between 10 and 100 at operating frequencies between 10 MHz and 1000 MHz; a second sheet including oriented non-magnetic, dielectric fibers; and means for holding surfaces of the first and second sheets adjacent one another so that principal planes of the sheets are generally parallel and permitting rotation of one sheet with respect to another about an axis normal to the principal planes.
Claim 22
Dependent Claim
85 words
An adjustable polarizing filter comprising: a first sheet containing oriented, ferrite particulate filled fibers, said ferrite filled fibers having a magnetic permeability between 10 and 100 at operating frequencies between 10 MHz and 1000 MHz; a second sheet including oriented non-magnetic, dielectric fibers; and means for holding surfaces of the first and second sheets adjacent one another so that principal planes of the sheets are generally parallel and permitting rotation of one sheet with respect to another about an axis normal to the principal planes.
Claim 23
Dependent Claim
20 words
The adjustable polarizing filter of claim 18 wherein said ferrite filled fibers have an aspect ratio of at least 50.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-03-01 | 1991-08-31 | 1992-03-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-03-01 | 1995-08-31 | 1996-03-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-03-01 | 1999-08-31 | 2000-03-01 | $7700.00 | Window Closed / Lapsed |