The influence of channel boundaries on remotely sensed target resonances

Abstract

Target resonances are unique characteristics of scatterers and serve to identify them unambiguously. In the vicinity of environmental boundaries, the way resonances are perceived by sensors is different than in the absence of boundaries. Thus, even though the resonances themselves do not change. the way in which they manifest themselves in the scattering cross section of scatterers as sensed at the receiver, changes near an environmental boundary. A formalism is developed to study this change and to assess the effect of boundaries upon the way elastic scatterers are excited into resonant vibration by incident sound waves. This formalism reduces to an earlier one developed [J. Acoust. Soc. Am. 73, 1–12 (1983)] for an infinite medium lacking boundaries. In general, the effect of boundaries on the resonance features present in the sonar cross section depends on the azimuthal wavenumber m, even for spherical scatterers. It also depends on the depths H and h of the elastic scatterer and the receiver, beneath t...