An Efficient Bi-Polar Near-Field Far-Field Transformation for Flat AUTs

This conference paper is devoted to an experimental assessment of a bi-polar near-field far-field (NFFF) transformation with probe compensation, which is particularly convenient from the data reduction standpoint when characterising a flat antenna under test (AUT). The proposed technique utilizes the non-redundant sampling representations of the electromagnetic fields for developing an efficient probe voltage sampling representation on the scan plane, which requires the knowledge of the NF bi-polar samples at a reduced number of sampling points. Then, these samples are suitably interpolated by a two-dimensional optimal sampling interpolation expansion to accurately reconstruct the plane-rectangular NF data needed by the standard Leach&Paris's NFFF transformation. To properly take into account the AUT geometry, a disc having diameter equal to the AUT largest dimension is adopted as modeling surface. Such a surface allows one a more effective AUT modeling from the NF data reduction stand-point than the other proposed modeling surfaces for quasi-planar AUTs (the oblate spheroid or the two-bowls), because it has the capability to reduce very significantly the related volumetric redundance, fitting very well the AUT geometry. Experimental results are shown to assess the efficacy of this NFFF transformation.