New approach to a constant beamwidth transducer
作者:
Peter H. Rogers,
A. L. Van Buren,
期刊:
The Journal of the Acoustical Society of America
(AIP Available online 1978)
卷期:
Volume 64,
issue 1
页码: 38-43
ISSN:0001-4966
年代: 1978
DOI:10.1121/1.381954
出版商: Acoustical Society of America
数据来源: AIP
摘要:
The theory of a broadband constant beamwidth transducer which is to be used primarily as a projector is presented. The transducer is a spherical cap of arbitrary half angle α shaded so that the normal velocity is equal toU0Pν(cos ϑ), wherePνis the Legendre function whose root of smallest angle occurs at ϑ=α. The required value for ν, the order of the Legendre function (which is not, in general, an integer) can be obtained to within 1% for α?1 radian from the approximation ν?0.5[(4.81/α)−1]. The transducer is shown to have uniform acoustic loading, extremely low sidelobes, and an essentially constant beam pattern for all frequencies above a certain cutoff frequency. Under piezoelectric drive the transducer is shown to have a flat transmitting current response over a broad band.
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