Laboratory tests on a NF-FF transformation technique from nonredundant bi-polar data

This communication concerns the experimental validation of a probe compensated near-field - far-field (NF-FF) transformation technique with bi-polar scanning for quasi-planar antennas requiring a minimum number of NF data. Such a technique properly exploits the nonredundant sampling representations of the electromagnetic fields to obtain an efficient representation of the voltage measured by the probe on the scanning plane in terms of the bi-polar NF samples. A double bowl, i.e. a surface formed by two circular bowls with the same aperture diameter, but eventually different lateral bends, is adopted to model the quasi-planar antenna under test. An optimal sampling interpolation formula is applied to reconstruct, in an efficient and accurate way, the NF data required by the classical plane-rectangular NF-FF transformation from the collected bi-polar ones. Thus, a remarkable reduction in the number of the NF data to be acquired and related acquisition time is gained. Some results of experimental tests, carried out at the Antenna Characterization Lab of the University of Salerno and assessing the effectiveness of the presented technique, are shown.