3-D Probe Positioning Errors Compensation in a Non-Redundant Spherical NF-FF Transformation

An effective two-steps technique to compensate known 3-D mispositioning errors, affecting the near-field (NF) measurements in a non-redundant spherical NF-far-field (NF-FF) transformation technique for quasi-planar antennas, is here developed. In the first step, a phase correction technique called spherical wave correction is applied to compensate the phase shifts originated by the deviations from the measurement sphere. In the second step, an iterative procedure is exploited to restore the NF samples at their exact locations from those determined at the previous step. Once the NF samples are retrieved at their exact position, an optimal sampling interpolation formula is employed to get the input NF data needed to perform the classical spherical NF-FF transformation technique. The effectiveness and the reliability of the approach are numerically assessed.