A new perspective in spherical near-field antenna measurements

An optimized Near-Field/Far-Field (NFFF) transformation technique for the characterization of aperture antennas in spherical geometry is presented. The optimized approach introduced by the Authors for the planar geometry is extended to the spherical one. The transformation is formulated as a linear inverse problem, and the number and the locations of the sampling points are chosen as the ones optimizing the singular value dynamics of the relevant operator to be inverted. The performance of the method is numerically evaluated in terms of both the accuracy and the reduction of the number of field samples against the standard approach.