Nonredundant near-field-far-field transformation from probe positioning errors affected bi-polar data

This work provides the experimental assessment of an efficient technique which allows the correction of known positioning errors in a near-field — far-field (NF-FF) transformation with bipolar scan requiring a minimum number of NF data. The NF-FF transformation uses a 2-D optimal sampling interpolation expansion, obtained by modeling the antenna under test with an oblate ellipsoid and applying the nonredundant sampling representations to the voltage measured by the probe, to accurately reconstruct the NF data needed by the classical plane-rectangular NF-FF transformation from the voltages samples at the points fixed by the representation. These unknown uniform samples are efficiently retrieved from the acquired positioning errors affected ones by applying a singular value decomposition based procedure. The so developed NF-FF transformation allows the accurate evaluation of the antenna far field from a nonredundant number of positioning errors affected NF data acquired through a bi-polar scanning. Some experimental results, carried out at the Antenna Characterization Lab of the University of Salerno and confirming the effectiveness of the proposed technique, are shown.