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US5949387A
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Frequency selective surface (FSS) filter for an antenna
Assignee: Northrop Grumman Systems Corp
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Filing: 1997-04-29
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Granted: 1999-09-07
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Expires: 2017-04-29
Abstract
Abstract A frequency selective surface filter (20 or 50) particularly useful in connection with a transmit antenna (10) for passing and rejecting signals in multiple frequency bands. According to one embodiment, the frequency selective surface filter (20) has a single conductive screen (24) disposed on a dielectric medium (22). The single-conductive screen (24) includes an array of parallel intersecting lines (26) and (28) providing low frequency filtering. The single-conductive screen (24) also includes an array of double-loop conductive elements each made up of an inner conductive loop (32) and an outer conductive loop (30). According to a second embodiment, the frequency selective surface filter (50) contains two dielectrically separated conductive layers including a first conductive layer (52) having an array of double-slots made up of an inner slot (64) and an outer slot (66). The double-slot configuration further includes a second conductive layer (60) made up of an array of single conductive loops (62).
Inventors
- 👤 Te-Kao Wu
- 👤 John J. Macek
- 👤 Mark E. Bever
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; H01Q15/0026; H01Q19/00; H01Q19/06; H01Q19/08
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
132 words
A frequency selective surface filter for providing multiple frequency rejection bands, said frequency selective surface filter comprising: a dielectric substrate that is substantially transparent to electromagnetic signal transmission; a square grid disposed on said dielectric substrate including a first plurality of conductors extending in a first direction and intersecting a second plurality of conductors extending in a second direction which is substantially perpendicular to the first direction, said square grid providing a first frequency rejection band; and a plurality of double-loop conductive elements, each of said double-loop conductive elements including an inner loop and an outer loop located in each region of the square grid, said outer loop encircling the inner loop, and said first loop providing a second frequency rejection band and said second loop providing a third frequency rejection band.
Claim 2
Dependent Claim
132 words
A frequency selective surface filter for providing multiple frequency rejection bands, said frequency selective surface filter comprising: a dielectric substrate that is substantially transparent to electromagnetic signal transmission; a square grid disposed on said dielectric substrate including a first plurality of conductors extending in a first direction and intersecting a second plurality of conductors extending in a second direction which is substantially perpendicular to the first direction, said square grid providing a first frequency rejection band; and a plurality of double-loop conductive elements, each of said double-loop conductive elements including an inner loop and an outer loop located in each region of the square grid, said outer loop encircling the inner loop, and said first loop providing a second frequency rejection band and said second loop providing a third frequency rejection band.
Claim 3
Dependent Claim
22 words
The frequency selective surface filter as defined in claim 1 wherein said dielectric substrate is provided as a thin substantially planar medium.
Claim 4
Dependent Claim
22 words
The frequency selective surface filter as defined in claim 1 wherein said inner and outer loops are each configured as square loops.
Claim 5
Dependent Claim
26 words
The frequency selective surface filter as defined in claim 1 wherein said frequency selective surface filter is disposed in communication with a multibeam phased array antenna.
Claim 6
Dependent Claim
45 words
The frequency selective surface filter as defined in claim 1 wherein said frequency selective surface filter is disposed in communication with a transmit antenna, said frequency selective surface filter filtering out higher frequency harmonics produced by non-linear characteristics of circuitry components in the transmit antenna.
Claim 7
Dependent Claim
116 words
A frequency selective surface filter comprising: a dielectric medium that is substantially transparent to electromagnetic signal transmission and having a top surface and a bottom surface; an array of double-loop slots provided in a first conductor material on one of the top and bottom surfaces of said dielectric medium, each of said double loop slots including an inner radiating slot encircled by an outer radiating slot for passing signals in a first frequency band and a second frequency band while rejecting signals in a first rejection band; and an array of conductive loop elements disposed on the other of said top and bottom surfaces of the dielectric layer, for rejecting signals in a second rejection band.
Claim 8
Dependent Claim
116 words
A frequency selective surface filter comprising: a dielectric medium that is substantially transparent to electromagnetic signal transmission and having a top surface and a bottom surface; an array of double-loop slots provided in a first conductor material on one of the top and bottom surfaces of said dielectric medium, each of said double loop slots including an inner radiating slot encircled by an outer radiating slot for passing signals in a first frequency band and a second frequency band while rejecting signals in a first rejection band; and an array of conductive loop elements disposed on the other of said top and bottom surfaces of the dielectric layer, for rejecting signals in a second rejection band.
Claim 9
Dependent Claim
26 words
The frequency selective surface filter as defined in claim 6 wherein said frequency selective surface filter is disposed in communication with a multibeam phased array antenna.
Claim 10
Dependent Claim
45 words
The frequency selective surface filter as defined in claim 6 wherein said frequency selective surface filter is disposed in communication with a transmit antenna, said frequency selective surface filter filtering out higher frequency harmonics produced by non-linear characteristics of circuitry components in the transmit antenna.
Claim 11
Dependent Claim
21 words
The frequency selective surface filter as defined in claim 6 wherein said dielectric medium has substantially planar top and bottom surfaces.
Claim 12
Dependent Claim
21 words
The frequency selective surface as defined in claim 6 wherein each of said conductive loop elements comprises a single conductive loop.
Claim 13
Dependent Claim
19 words
The frequency selective surface as defined in claim 6 wherein said conductive loop elements are configured as square loops.
Claim 14
Dependent Claim
19 words
The frequency selective surface as defined in claim 6 wherein said slots each are configured as square loop slots.
Claim 15
Dependent Claim
33 words
The frequency selective surface as defined in claim 6 wherein said dielectric medium comprises: a first thin dielectric substrate providing the top surface; and a second thin dielectric substrate providing the bottom surface.
Claim 16
Dependent Claim
28 words
The frequency selective surface as defined in claim 13 wherein said dielectric medium further comprises a dielectric isolation layer disposed between the first and second thin dielectric substrates.
Claim 17
Dependent Claim
88 words
An antenna comprising: one or more radiating elements for radiating electromagnetic radiation; transmit circuitry for generating signals for transmission from said one or more radiating elements; and a frequency selective surface disposed in communication with the one or more radiating elements so as to provide selective frequency filtering, said frequency selective surface filter including a thin dielectric medium that is transparent to electromagnetic signal transmission said frequency surface further including frequency dependent elements for providing multiple frequency rejection bands to reject unwanted signals within the multiple frequency bands.
Claim 18
Dependent Claim
88 words
An antenna comprising: one or more radiating elements for radiating electromagnetic radiation; transmit circuitry for generating signals for transmission from said one or more radiating elements; and a frequency selective surface disposed in communication with the one or more radiating elements so as to provide selective frequency filtering, said frequency selective surface filter including a thin dielectric medium that is transparent to electromagnetic signal transmission said frequency surface further including frequency dependent elements for providing multiple frequency rejection bands to reject unwanted signals within the multiple frequency bands.
Claim 19
Dependent Claim
113 words
The antenna as defined in claim 15 wherein said frequency selective surface further comprises: a square grid including a first plurality of conductors extending in a first direction and intersecting a second plurality of conductors extending in a second direction which is substantially perpendicular to the first direction, said square grid providing a first frequency rejection band; and a plurality of double-loop conductive elements, each of said double-loop conductive elements including an inner loop and an outer loop located in each region of the square grid, said outer loop encircling the inner loop, and said first loop providing a second frequency rejection band and said second loop providing a third frequency rejection band.
Claim 20
Dependent Claim
104 words
The antenna as defined in claim 15 wherein said frequency selective surface further comprises: an array of double-loop slots provided in a first conductor material on one of the top and bottom surfaces of said dielectric medium, each of said double loop slots including an inner radiating slot encircled by an outer radiating slot for passing signals in a first frequency band and a second frequency band while rejecting signals in a first rejection band; and an array of conductive loop elements disposed on the other of said top and bottom surfaces of the dielectric layer, for rejecting signals in a second rejection band.
Claim 21
Dependent Claim
19 words
The antenna as defined in claim 15 wherein said one or more radiating elements comprises a multibeam phased array.
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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) | 2002-09-06 | 2003-03-08 | 2003-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-09-06 | 2007-03-08 | 2007-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-09-06 | 2011-03-08 | 2011-09-07 | $7700.00 | Window Closed / Lapsed |