Experimental evidences on the effectiveness of a nonredundant spherical spiral NF/FF transformation for offset mounted quasi-planar AUTs

The work aims to provide the experimental assessment of a recently proposed near-field/far-field (NF/FF) transformation technique with spherical spiral scan, that, by properly exploiting the theoretical bases on the nonredundant representation of electromagnetic fields and on the spiral scans for nonvolumetric antennas, is able to account for mountings of the antennas under test (AUTs) in offset configuration. It will be shown that, to characterize an AUT with a quasi-planar geometry, suitably modelled by a flexible surface made by two circular bowls of equal apertures and possibly different lateral bends, the developed technique employs the same amount of NF data both for offset and onset AUT mountings, since this amount relies only on the area of the surface that contains the antenna. The experimental results will further confirm its practical efficacy