Experimental Assessment of an Effective Near-Field-Far-Field Transformation With Spherical Spiral Scanning for Quasi-Planar Antennas

Experimental tests on a near-field-far-field (NF-FF) transformation technique with spherical spiral scanning suitable for quasi-planar antennas are presented in this letter. Such a technique is based on the nonredundant sampling representations of the electromagnetic fields and employs an oblate ellipsoid to model the antenna under test. A two-dimensional optimal sampling interpolation formula is then employed to recover the NF data at any point on the scanning sphere and, in particular, at those needed by the classical spherical NF-FF transformation. It is so possible to lower the number of needed measurements, as well as the time required to acquire the data. Both the reported NF and FF reconstructions assess the effectiveness of the technique.