A HYBRID METHOD FOR PREDICTING THE COMPLETE SCATTERING FUNCTION FROM LIMITED DATA

The three-dimensional acoustic scattering function of an object is ver y difficult and expensive to measure, even in controlled experiments. Usually one is limited to sampling this function at a limited number o f monostatic angles and perhaps at a few bistatic angles in a single p lane. However, the three-dimensional function is controlled by relativ ely few degrees of freedom at low frequencies. By using a computationa l model to generate the far-field propagator function for the object, and applying reciprocity conditions as a constraint, a least-squares p roblem can be formulated to estimate the radiating part of the surface source strength. Singular value decomposition of the propagator funct ion is used to identify the efficient radiating modes. Once the surfac e source density is determined by solving the least-squares problem, t he full three-dimensional scattering function can be reconstructed. Th e theoretical basis for this technique will be presented, along with a discussion of results obtained to date. Practical issues dealing with the numerical implementation and computational efficiency will also b e discussed. (C) 1995 Acoustical Society of America.