US4169268A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Metallic grating spatial filter for directional beam forming antenna
Assignee: United States Department of the Air Force
•
Filing: 1978-05-11
•
Granted: 1979-09-25
•
Expires: 1998-05-11
Abstract
Abstract Sidelobe suppression and other beam transmission property manipulations in directional beam forming antennas is accomplished by means of a spatial filter. The filter geometry consists of a plurality of metallic gratings separated by air or other low dielectric constant dielectric substance. The filter is placed directly over the antenna radiating aperture and is encompassed by a tunnel structure of electromagnetic wave energy absorbing material. The shunt susceptance characteristics of the metallic gratings together with the integrating spacing distances are synthesized in a manner that effects full transmission of beam power in a selected beam direction while offering substantial rejection of it in other directions.
Inventors
- 👤 Allan C. Schell
- 👤 Robert J. Mailloux
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 18:07
CPC Classifications
H; H01; H01Q; H01Q15/00; H01Q15/0006; H01Q15/0053; H01Q17/00; H01Q17/001
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
120 words
A spatial filter for a directional beam forming antenna comprising a plurality of spaced, juxtaposed planar periodic metallic structures positioned proximate to said antenna and in intercepting relationship with electromagnetic wave energy transmitted and received thereby, said planar periodic metallic structures being separated by dielectric medium and spaced at distances that effect substantially complete cancellation of electromagnetic wave energy reflected by said planar metallic periodic metallic structures for a given beam direction, said planar periodic metallic structures being commensurate and in register at periodic intervals, the periodicity of said periodic intervals being not more than one half wavelength, and each said planer periodic metallic structure having an equivalent circuit that presents a shunt susceptance to electromagnetic wave energy received thereby.
Claim 2
Dependent Claim
120 words
A spatial filter for a directional beam forming antenna comprising a plurality of spaced, juxtaposed planar periodic metallic structures positioned proximate to said antenna and in intercepting relationship with electromagnetic wave energy transmitted and received thereby, said planar periodic metallic structures being separated by dielectric medium and spaced at distances that effect substantially complete cancellation of electromagnetic wave energy reflected by said planar metallic periodic metallic structures for a given beam direction, said planar periodic metallic structures being commensurate and in register at periodic intervals, the periodicity of said periodic intervals being not more than one half wavelength, and each said planer periodic metallic structure having an equivalent circuit that presents a shunt susceptance to electromagnetic wave energy received thereby.
Claim 3
Dependent Claim
27 words
A spatial filter for a directional beam forming antenna as defined in claim 1 wherein said planar periodic metallic structures are non-resonant at the filter operating frequency.
Claim 4
Dependent Claim
23 words
A spatial filter for a directional beam forming antenna as defined in claim 1 wherein said planar periodic metallic structures are metallic gratings.
Claim 5
Dependent Claim
29 words
A spatial filter for a directional beam forming antenna as defined in claim 1 wherein said planar periodic metallic structures are metallic sheet member having periodically disposed apertures therein.
Claim 6
Dependent Claim
26 words
A spatial filter for a directional beam forming antenna as defined in claim 3 wherein the grating element dimensions and spacings for all gratings are alike.
Claim 7
Dependent Claim
27 words
A spatial filter for a directional beam forming antenna as defined in claim 3 wherein the grating element dimensions and spacings for all gratings are not alike.
Claim 8
Dependent Claim
33 words
A spatial filter for a directional beam forming antenna as defined in claim 1 including an electromagnetic wave energy absorbing tunnel member in peripheral relationship to said spaced juxtaposed planar periodic metallic structures.
References Cited (Backward Citations)
GB665747A
Cited
US2684725A
Cited
US2763860A
Cited
US2756424A
Cited
FR1058285A
Cited
US3708796A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-09-24 | 1983-03-26 | 1983-09-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-09-24 | 1987-03-26 | 1987-09-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-09-24 | 1991-03-26 | 1991-09-25 | $7700.00 | Window Closed / Lapsed |