A non-redundant spherical NF/FF transformation for an aut measured over an infinite perfectly conducting ground plane

An efficient spherical near-field to far-field (NF/FF) transformation, using a minimum number of NF data, which, due to the presence of an infinite perfectly conducting ground plane, are collected only over the upper hemisphere, is proposed in this work. It is developed by properly applying the non-redundant sampling representations of electromagnetic fields to the voltage acquired by a non-directive probe and assuming, as required by the image principle, the considered AUT and its image as contained in a prolate spheroid. Once the non-redundant NF data over the lower hemisphere have been properly synthesized from the voltage samples acquired on the upper one, an efficient 2-D optimal sampling interpolation scheme is then used to reconstruct the NF data required by the standard spherical NF/FF transformation. Numerical simulations, assessing the accuracy of the developed non-redundant spherical NF/FF transformation, are shown.