摘要
In this paper the physical acoustic method or the Kirchhoff approximation is extended to treat the scattering of a nonrigid surface in order to estimate the target strength of targets with absorbing coatings. By using the locally plane wave approximation, the relationship between the sound pressure and its normal derivative on the surface can be represented by the plane wave reflection coefficient and the acoustic impedance of the surface. The resulting modified Kirchhoff approximation involves the plane wave reflection coefficient. For a impedance sphere, a comparison between the physical acoustic method and the exact solution shows that the physical acoustic method still is a good approximation at higher ka values.
In this paper the physical acoustic method or the Kirchhoff approximation is extended to treat the scattering of a nonrigid surface in order to estimate the target strength of targets with absorbing coatings. By using the locally plane wave approximation, the relationship between the sound pressure and its normal derivative on the surface can be represented by the plane wave reflection coefficient and the acoustic impedance of the surface. The resulting modified Kirchhoff approximation involves the plane wave reflection coefficient. For a impedance sphere, a comparison between the physical acoustic method and the exact solution shows that the physical acoustic method still is a good approximation at higher ka values.
