Elementary Results for Scattering by Large Ellipsoids
作者:
James E. Burke,
Victor Twersky,
期刊:
The Journal of the Acoustical Society of America
(AIP Available online 1965)
卷期:
Volume 38,
issue 4
页码: 589-598
ISSN:0001-4966
年代: 1965
DOI:10.1121/1.1909752
出版商: Acoustical Society of America
数据来源: AIP
摘要:
Elementary high‐frequency approximations for scattering by an arbitrary body are specialized to ellipsoids and applied in detail for source and observation points at distances large compared to the scatterer's size. It is shown, for example, that, if the direction of observation is varied in a fixed plane containing the direction of incidence, then except for the near‐forward direction (“shadow region”) the first approximation for the far‐distant field for a given ellipsoid is specified by a “universal curve.” In particular, if the fixed plane contains an axis of the ellipsoid, then there is a unique curve for the intensity versus the angle measured from the reflection of the direction of incidence in the contained axis. For the special case of the spheroid, the field on the “axially specular” cone (the cone defined by the angle of incidence with the axis of rotation) remains constant until one gets near the shadow region, and the fields on adjacent cones (i.e., with generators at other than the specular angle with the axis) vary slowly with the azimuthal angle; for many practical purposes, we may neglect the slowly varying effects and approximate the reflected intensity pattern in the vicinity of the axially specular cone by a conical lobe of revolution. Numerical examples are given for a family of spheroids; e.g., we determine contours of constant intensity on a plane containing the source as functions of the spheroid's distance from the plane, etc.
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