Near-field to far-field projection algorithm for free-field or buried scatterer

A near-field to far-field projection algorithm is applied to a structure in the free-field case and generalized to a buried scatterer. The method of superposition is applied where the scattered field produced by the target may be approximated by the field produced by a number of point sources placed near the target. The source strengths are determined by requiring the field they produce to satisfy boundary conditions on the measurement surface. In the free-field case, the expression of the Green's function is simple. In the buried case, the two-domain Green's function may be expressed as an integral over special functions. Once the source strengths are determined, the far-field is computed as a superposition of the fields produced by the individual sources. The algorithm is tested on numerically generated data.