Patent US5373302A successfully refreshed from Google Patents.
US5373302A
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Double-loop frequency selective surfaces for multi frequency division multiplexing in a dual reflector antenna
Assignee: National Aeronautics and Space Administration
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Filing: 1993-09-23
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Granted: 1994-12-13
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Expires: 2013-09-23
Abstract
Abstract A multireflector antenna utilizes a frequency-selective surface (FSS) in a subreflector to allow signals in two different RF bands to be selectively reflected back into a main reflector and to allow signals in other RF bands to be transmitted through it to the main reflector for primary focus transmission. A first approach requires only one FSS at the subreflector which may be an array of double-square-loop conductive elements. A second approach uses two FSS's at the subreflector which may be an array of either double-square-loop (DSL) or double-ring (DR). In the case of DR elements, they may be advantageously arranged in a triangular array instead of the rectangular array for the DSL elements.
Inventors
- 👤 Te-Kao Wu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 15:57
CPC Classifications
H; H01; H01Q; H01Q15/00; H01Q15/0006; H01Q15/0013; H01Q15/0033; H01Q5/00; H01Q5/40; H01Q5/45
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
270 words
A dual-reflector system for frequency division multiplexing of four signals, each in a separate one of four radio-frequency bands comprising first and second radio-frequency signal reflectors facing each other, said second radio-frequency signal reflector having double-loop conductive elements arrayed for selective reflection of two signals in two separate radio-frequency bands, first and second feed systems, each feed system for transmission of a different selected set of two of said radio-frequency signals in separate radio-frequency bands, said second radio-frequency signal reflector having said arrayed double-loop conductive elements chosen for passing said two signals in different radio-frequency bands from said first feed system through said second radio-frequency signal reflector in a direction toward said first radio-frequency signal reflector, and for reflecting said two radio-frequency signals from said second feed system protruding through said first radio-frequency signal reflector back to said first radio-frequency signal reflector, said first radio-frequency signal reflector being chosen to reflect all of said sets of two radio-frequency signals from said first and second feed systems for transmission of said radio-frequency signals from said first feed system and said radio-frequency signal from said second feed system, wherein said arrayed double-loop conductive elements of said second radio-frequency signal reflector comprises a plurality of double-loop conductive elements on a dielectric sheet of known dielectric constant arranged to form at least one grid of elements, and dimensions of said double-loop conductive elements of said frequency-selective surface of said second radio-frequency signal reflector being chosen for passing said two signals in separate radio-frequency bands transmitted said first feed system and selective reflection of signals transmitted in separate radio-frequency bands by said second feed system.
Claim 2
Dependent Claim
270 words
A dual-reflector system for frequency division multiplexing of four signals, each in a separate one of four radio-frequency bands comprising first and second radio-frequency signal reflectors facing each other, said second radio-frequency signal reflector having double-loop conductive elements arrayed for selective reflection of two signals in two separate radio-frequency bands, first and second feed systems, each feed system for transmission of a different selected set of two of said radio-frequency signals in separate radio-frequency bands, said second radio-frequency signal reflector having said arrayed double-loop conductive elements chosen for passing said two signals in different radio-frequency bands from said first feed system through said second radio-frequency signal reflector in a direction toward said first radio-frequency signal reflector, and for reflecting said two radio-frequency signals from said second feed system protruding through said first radio-frequency signal reflector back to said first radio-frequency signal reflector, said first radio-frequency signal reflector being chosen to reflect all of said sets of two radio-frequency signals from said first and second feed systems for transmission of said radio-frequency signals from said first feed system and said radio-frequency signal from said second feed system, wherein said arrayed double-loop conductive elements of said second radio-frequency signal reflector comprises a plurality of double-loop conductive elements on a dielectric sheet of known dielectric constant arranged to form at least one grid of elements, and dimensions of said double-loop conductive elements of said frequency-selective surface of said second radio-frequency signal reflector being chosen for passing said two signals in separate radio-frequency bands transmitted said first feed system and selective reflection of signals transmitted in separate radio-frequency bands by said second feed system.
Claim 3
Dependent Claim
164 words
A dual-reflector system as defined in claim 1 wherein said arrayed double-loop conductive elements of said second reflector comprise first and second grids of double-loop conductive elements being positioned to receive direct radiation of said two radio-frequency signals transmitted by said second feed system, and dimensions of said first grid of double-loop conductive elements of said second radio-frequency signal reflector are chosen for selective reflection of one of said two radio-frequency signals in separate radio-frequency bands transmitted by said second feed system while passing the other of said two radio-frequency signals in separate radio-freguency bands transmitted by said second feed system, and for also passing said radio-frequency signals in separate radio-frequency bands transmitted by said first feed system to said first radio-frequency signal reflector, and dimensions of said second grid of double-loop conductive elements of said second radio-frequency signal reflector are chosen for selective reflection of a second one of said two radio-frequency signals in separate radio-frequency bands transmitted by said second feed system.
Claim 4
Dependent Claim
28 words
A dual-reflector system as defined in claim 2 wherein said double-loop conductive elements of said first and second grids of said second radio-frequency signal reflector are circular-loop elements.
Claim 5
Dependent Claim
29 words
A dual-reflector system as defined in claim 2 wherein said double-loop conductive elements of said first and second grids of said second radio-frequency signal reflector are circular-loop conductive elements.
Claim 6
Dependent Claim
54 words
A dual-reflector system as defined in claim 4 wherein said circular-loop conductive elements are arranged in a triangular array such that the distances of every circular-loop conductive element of said grid to adjacent circular-loop conductive elements are equal and therefore each circular-loop conductive element forms with two adjacent circular-loop conductive elements an equilateral triangle.
Claim 7
Dependent Claim
77 words
A dual-reflector system as defined in claim 1 wherein said frequency-selective surface of said second radio-frequency reflector comprises a grid of double-square-loop conductive elements on said sheet of known dielectric constant, said double-square-loop conductive elements being designed as to dimensions and spacing on said sheet of known dielectric constant to receive and reflect direct radiation of said two radio-frequency signals transmitted by said second feed systems while passing any radio-frequency signal transmitted by said first feed system.
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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) | 1997-12-12 | 1998-06-13 | 1998-12-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-12-12 | 2002-06-13 | 2002-12-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-12-12 | 2006-06-13 | 2006-12-13 | $7700.00 | Window Closed / Lapsed |