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US4743919A
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Microwave frequency selective surface having fibrous ceramic body
Assignee: Raytheon Co
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Filing: 1986-10-07
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Granted: 1988-05-10
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Expires: 2006-10-07
Abstract
Abstract A frequency selective surface having a fibrous ceramic material body and a metallic grid on a reflecting face thereof. The body is formed by bonding a mass of silicon dioxide fibers together at their intersection points, as with a fusing agent such as boron nitride in a sintering process, resulting in an array of fibers with cellular porosity intentionally distributed through the body to reduce its density. Other types of ceramic fibers can be used either alone or in combination with the silicon dioxide fibers. The grid is attached to the reflecting surface or deposited thereon. The frequency selective surface finds particular utility in satellite microwave communications satellites.
Inventors
- 👤 Stanley S. Chang
- 👤 Hui Bau
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:53
CPC Classifications
H; H01; H01Q; H01Q15/00; H01Q15/0006; H01Q15/0013
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
76 words
A frequency selective surface for selectively reflecting microwave radiation, comprising: a body of a cellular ceramic material wherein a plurality of ceramic fibers are bonded together at their points of intersection to form a rigid structure having open cells dispersed therethrough and a reflecting face, and a metallic grid on said reflecting face, said grid being a repeating pattern of elements, which pattern passes a first frequency and reflects a second frequency of incident microwave radiation.
Claim 2
Dependent Claim
76 words
A frequency selective surface for selectively reflecting microwave radiation, comprising: a body of a cellular ceramic material wherein a plurality of ceramic fibers are bonded together at their points of intersection to form a rigid structure having open cells dispersed therethrough and a reflecting face, and a metallic grid on said reflecting face, said grid being a repeating pattern of elements, which pattern passes a first frequency and reflects a second frequency of incident microwave radiation.
Claim 3
Dependent Claim
21 words
The frequency selective surface of claim 1, wherein said grid is supported on a nonmetallic film attached to said reflecting face.
Claim 4
Dependent Claim
15 words
The frequency selective surface of claim 1, wherein said grid is about one micrometer thick.
Claim 5
Dependent Claim
16 words
The frequency selective surface of claim 1, wherein said grid is deposited upon said reflecting face.
Claim 6
Dependent Claim
28 words
The frequency selective surface of claim 1, wherein said grid is formed of a metal selected from the group consisting of gold, copper and tungsten, and alloys thereof.
Claim 7
Dependent Claim
13 words
The frequency selective surface of claim 1, wherein said reflecting face is flat.
Claim 8
Dependent Claim
18 words
The frequency selective surface of claim 1, wherein said grid comprises a repetitive rectilinear pattern of Jerusalem crosses.
Claim 9
Dependent Claim
15 words
The frequency selective surface of claim 1, wherein said ceramic fibers include silicon dioxide fibers.
Claim 10
Dependent Claim
19 words
The frequency selective surface of claim 1, wherein said ceramic fibers include silicon dioxide fibers and aluminum oxide fibers.
Claim 11
Dependent Claim
18 words
The frequency selective surface of claim 1, wherein said ceramic fibers are fused together by a fusing agent.
Claim 12
Dependent Claim
14 words
The frequency selective surface of claim 10, wherein said fusing agent is boron nitride.
Claim 13
Dependent Claim
35 words
The frequency selective surface of claim 1, wherein the composition of said body in weight percent is about 74 percent silicon dioxide, 20 percent aluminum oxide, 3 percent boron nitride, and 3 percent silicon carbide.
Claim 14
Dependent Claim
31 words
The frequency selective surface of claim 1 wherein said cellular ceramic material is arrayed in layers lying parallel to said reflecting face, adjacent layers having different densities of said ceramic material.
Claim 15
Dependent Claim
24 words
The frequency selective surface of claim 1, wherein the density of said body is from about 0.1 to about 0.5 grams per cubic centimeter.
Claim 16
Dependent Claim
65 words
A frequency selective surface for selectively reflecting microwave radiation, comprising: a body of a cellular ceramic material wherein a plurality of ceramic fibers are bonded together at their points of intersection to form a rigid structure having open cells dispersed therethrough and a reflecting face; and means on said reflecting face for passing a first frequency and reflecting a second frequency of incident microwave radiation.
Claim 17
Dependent Claim
65 words
A frequency selective surface for selectively reflecting microwave radiation, comprising: a body of a cellular ceramic material wherein a plurality of ceramic fibers are bonded together at their points of intersection to form a rigid structure having open cells dispersed therethrough and a reflecting face; and means on said reflecting face for passing a first frequency and reflecting a second frequency of incident microwave radiation.
Claim 18
Dependent Claim
19 words
The frequency selective surface of claim 15, wherein said body is curved concavely in respect to said reflecting face.
Claim 19
Dependent Claim
17 words
The frequency selective surface of claim 15, wherein said means is a grid of regularly repeating elements.
References Cited (Backward Citations)
US4652891A
Cited
US4656487A
Cited
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1991-05-10 | 1991-11-09 | 1992-05-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-05-10 | 1995-11-09 | 1996-05-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-05-10 | 1999-11-09 | 2000-05-10 | $7700.00 | Window Closed / Lapsed |