Far field reconstruction from positioning error affected near-field data acquired via a nonredundant spherical scanning

In this communication, an efficient approach to compensate known positioning errors in a near-field - far-field (NF-FF) transformation with spherical scanning for quasi-planar antennas is experimentally validated. Such an approach is based on a nonredundant sampling representation of the voltage measured by the probe, obtained by assuming the antenna under test as enclosed in an oblate ellipsoid, a modelling particularly suitable for dealing with quasi-planar radiating sources. It employs the singular value decomposition method to retrieve the nonredundant NF data at the points fixed by the sampling representation from the acquired irregularly distributed ones. These last are assumed lying on nonuniform parallels so that the two-dimensional problem is reduced to the solution of two independent one-dimensional ones. The NF data needed to carry out the classical spherical NF-FF transformation are then efficiently evaluated from the nonredundant NF data by using an optimal sampling interpolation algorithm. Experimental tests, performed at the Antenna Characterization Lab of the University of Salerno and assessing the effectiveness of the technique, are shown.