US4240080A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Short backfire antenna with sum and error patterns
Assignee: United States Department of the Army
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Filing: 1979-11-19
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Granted: 1980-12-16
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Expires: 1999-11-19
Abstract
Abstract A simplified short backfire directional antenna provides both sum and erroradiation patterns in the H-plane. Three parallel dipoles are mounted above a pan-type reflector, with a small metal reflector disc over the dipoles. The center dipole is excited to produce a sum pattern and the two end dipoles are excited out of phase to provide an error pattern with a broadside null in the H-plane. Alternatively, a hybrid circuit may be used with a pair of parallel dipoles to generate the desired patterns. Improved gain and resolution are achieved with a small antenna array.
Inventors
- 👤 Oakley M. Woodward
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:15
CPC Classifications
H; H01; H01Q; H01Q25/00; H01Q25/02; H01Q19/00; H01Q19/10; H01Q19/18; H01Q19/185
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
104 words
A radio-frequency directional antenna comprising: a first reflector plate having an axially extending peripheral rim; a second reflector disc disposed centrally and parallel to said first plate and spaced from said plate and rim at a given distance along a common longitudinal axis, the width of said second reflector being a relatively small fraction of that of said first reflector; a plurality of parallel dipole feed elements positioned symmetrically about said axis at a given distance between said first and second reflectors; and means for applying electromagnetic energy to said dipole feed elements to provide sum and error radiation distribution patterns in the H-plane.
Claim 2
Dependent Claim
104 words
A radio-frequency directional antenna comprising: a first reflector plate having an axially extending peripheral rim; a second reflector disc disposed centrally and parallel to said first plate and spaced from said plate and rim at a given distance along a common longitudinal axis, the width of said second reflector being a relatively small fraction of that of said first reflector; a plurality of parallel dipole feed elements positioned symmetrically about said axis at a given distance between said first and second reflectors; and means for applying electromagnetic energy to said dipole feed elements to provide sum and error radiation distribution patterns in the H-plane.
Claim 3
Dependent Claim
72 words
The antenna of claim 1 wherein said plurality of dipole elements includes a center dipole and a pair of outer dipoles, each of said pair being 180 degrees out of phase with respect to the other, said means for applying electromagnetic energy to said center dipole producing a sum pattern and said means for applying said energy to said outer dipoles producing an error pattern having a broadside null in the H-plane.
Claim 4
Dependent Claim
29 words
The antenna of claim 1 including support means for said plurality of dipoles, said support means extending from said first reflector plate and being in the form of baluns.
Claim 5
Dependent Claim
65 words
The antenna of claim 1 wherein said first reflector plate is approximately two wavelengths in width, said second reflector is about 0.4 wavelength in width, said rim is about 0.25 wavelength in height, said dipoles are spaced about 0.25 wavelength from said first reflector plate, and said second reflector disc is spaced about 0.05 wavelength from said first reflector to form a resonant cavity therebetween.
Claim 6
Dependent Claim
21 words
The antenna of claim 2 wherein said means for applying energy to said outer dipoles includes feed lines of equal length.
Claim 7
Dependent Claim
30 words
The antenna of claim 2 including support means for said second reflector and said plurality of dipoles, said support means including a balun supporting said center dipole and second reflector.
Claim 8
Dependent Claim
25 words
The antenna of claim 2 wherein the sum pattern amplitude exceeds the error pattern amplitude in the angular region of the error pattern broadside null.
Claim 9
Dependent Claim
27 words
The antenna of claim 5 wherein said feed line lengths are selected to de-tune the outer dipoles to minimize pattern interaction in the sum mode of operation.
Claim 10
Dependent Claim
46 words
The antenna of claim 1 wherein said plurality of dipole elements includes a pair of dipoles, said means for applying electromagnetic energy including means for applying said energy in-phase to said pair of dipoles to produce said sum pattern and out-of-phase to produce said error pattern.
Claim 11
Dependent Claim
40 words
The antenna of claim 9 wherein said means for applying said energy out-of-phase includes a hybrid ring connected between said pair of dipoles and having connections at opposite ends of said hybrid ring for applying said energy in-phase and out-of-phase.
References Cited (Backward Citations)
US3742513A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-12-16 | 1984-06-16 | 1984-12-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-16 | 1988-06-16 | 1988-12-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-16 | 1992-06-16 | 1992-12-16 | $7700.00 | Window Closed / Lapsed |