A Two Steps Procedure to Compensate for 3-D Positioning Errors in a Non-Redundant NF/FF Transformation with Helicoidal Scan

An efficient way to correct for known 3-D mispositioning errors in the non-redundant near-fieldlfar-field (NFIFF) trans-formation with helicoidal scan, adopting a prolate spheroidal modeling of the antenna, is here presented. It involves two steps. In the former, the errors caused by displacements of the gathered NF samples from the scan cylinder are compensated with a proper phase correction named cylindrical wave correction. The latter employs an it-erative technique for the retrieval of the correctly positioned samples from those got after the first step, which are altered by 2-D position errors. At last, a 2-D optimal sampling interpolation expansion is employed to precisely evaluate the huge amount of NF data for the classical cylindrical NF/FF transformation. Numerical results, which assess the efficacy of the devised method, are provided.