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US4328569A
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Array shading for a broadband constant directivity transducer
Assignee: United States Department of the Navy
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Filing: 1979-11-14
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Granted: 1982-05-04
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Expires: 1999-11-14
Abstract
Abstract A broadband directional transducer which provides a beam pattern that is essentially constant for all frequencies above a certain cutoff frequency, an acoustic pressure angular distribution that is virtually independent of the distance from the transducer and no side lobes, includes an array of isophase, omnidirectional electro-acoustic elements on a spherical shell, each element being amplitude-shaded according to the shading function ##EQU1## where n is a positive integer, and θ is an angle measured from the axis of the spherical surface to a shaded element.
Inventors
- 👤 W. James Trott
- 👤 Jacek Jarzynski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 07:58
CPC Classifications
G; G10; G10K; G10K11/00; G10K11/18; G10K11/26; Y; Y10; Y10S; Y10S367/00; Y10S367/905
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
104 words
A transducer for transmitting and receiving acoustical energy in a surrounding fluid medium, and having an essentially constant beam pattern for all operating frequencies above a cutoff frequency, comprising: a spherical shell having an axis of symmetry, said shell having a circumferential arc b subtending a half-angle α, said half-angle α being measured from the axis of symmetry of said shell, said shell including an array of isophase, omnidirectional electro-acoustic elements, each element being amplitude-shaded in accordance with ##EQU8## where n is a positive integer, and θ is the angle measured from the axis of said shell to the center of the shaded element.
Claim 2
Dependent Claim
104 words
A transducer for transmitting and receiving acoustical energy in a surrounding fluid medium, and having an essentially constant beam pattern for all operating frequencies above a cutoff frequency, comprising: a spherical shell having an axis of symmetry, said shell having a circumferential arc b subtending a half-angle α, said half-angle α being measured from the axis of symmetry of said shell, said shell including an array of isophase, omnidirectional electro-acoustic elements, each element being amplitude-shaded in accordance with ##EQU8## where n is a positive integer, and θ is the angle measured from the axis of said shell to the center of the shaded element.
Claim 3
Dependent Claim
54 words
The transducer of claim 1, wherein said cutoff frequency is a function of the half-angle α and the arc b and can be obtained from the approximation f.sub.c =c[1100+(919/α)]/(1500 b), where b is in meters, α is in radians, and c is the sound speed of the surrounding fluid medium in meters per second.
Claim 4
Dependent Claim
20 words
The transducer of claim 1, wherein said elements are spaced about said shell, the spacing between elements being approximately constant.
Claim 5
Dependent Claim
13 words
The transducer of claim 1, wherein said elements are formed from piezoelectric material.
Claim 6
Dependent Claim
22 words
The transducer of claim 1, wherein said elements are small relative to the wavelength λ (less than λ/2) of said acoustical energy.
Claim 7
Dependent Claim
36 words
The transducer of claim 1, wherein 0<α≦π/2, n=1, 2, 3, . . . , and 0≦θ≦π/2 for a bidirectional transducer and 0<α≦π, n=0, 1, 2, 3, . . . , and 0<θ≦π for a unidirectional transducer.
Claim 8
Dependent Claim
20 words
The transducer of claim 3, wherein said spacing is less than 0.8 of a wavelength λ of said acoustical energy.
References Cited (Backward Citations)
US3805226A
Cited
US4156863A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-05-03 | 1985-11-02 | 1986-05-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-05-03 | 1989-11-02 | 1990-05-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-05-03 | 1993-11-02 | 1994-05-04 | $7700.00 | Window Closed / Lapsed |