Laboratory tests on a nonredundant near-field to far-field transformation with spherical scanning for long antennas

The experimental validation of a nonredundant near-field - far-field (NF-FF) transformation with spherical scanning suitable for electrically long antennas is provided in this work. Such a transformation technique relies on a nonredundant sampling representation of the voltage measured by the probe, obtained by modelling the antenna under test as enclosed in a cylinder ended in two half spheres. An optimal sampling interpolation expansion is then applied to accurately reconstruct the NF data needed by the classical spherical NF-FF transformation from the collected nonredundant ones. Thus, the number of NF data to be acquired and the related measurement time can be drastically reduced. Experimental tests, performed at the UNISA Antenna Characterization Lab and assessing the validity of the technique, are reported.