Numerical and Experimental Investigations of Transformations of Near-field to Far-field Scattering Measurements

Due to the size of a target and measurement constraints, the measurements of monostatic acoustic scattering are often made in the near field of the target. For many applications, it is an estimate of the far‐field target scattering strength, which is desired. In this presentation some model‐based inversion techniques, which can be used to predict far‐field monostatic target strengths as a function of aspect angle, are derived. In particular, a set of near‐field measurements is used in an inversion scheme to compute coefficients for either a linear array of point scatterers or for a generalized Kirchhoff model of the target. The resulting model is then used to predict the far field scattering amplitudes. Simulated and experimental data are used to illustrate the accuracy of the proposed methods.