Laboratory Tests Validating a Non-Redundant NF/FF Transformation with Spherical Spiral Scan for Non-Centered Mounted Long Antennas

The recently proposed near-field/far-field (NF/FF) transformation technique with spherical spiral scan, which, by properly exploiting the non-redundant representations of electromagnetic fields and the unified theory of spiral scans for non-volumetric antennas under test (AUTs), allows one to properly account for a mounting of an elongated AUT in offset configuration, is here experimentally validated. It is based on the prolate spheroidal source modelling and requires the same number of NF data as in the case of an onset AUT mounting, depending such a number only on the surface of the adopted AUT modelling. Moreover, it makes use of an efficient 2-D optimal sampling interpolation formula to recover the NF data needed to perform the standard NF/FF transformation, whose amount is related to the radius of the minimum sphere enclosing the AUT and centred at the scanning sphere centre. As it will be shown, the experimental results will further confirm the practical effectiveness of the proposed technique.