Direct far-field reconstruction from near-field data acquired through a helicoidal scanning

A near-field – far-field transformation with helicoidal scanning for elongated antennas, which allows the evaluation of the antenna far field directly from a nonredundant number of data without interpolating them, is here proposed. It relies on a nonredundant sampling representation of electromagnetic fields and employs a flexible source modelling suitable for long antennas to determine the number of helix turns. Instead, the number of data on each turn is fixed by the minimum cylinder rule, as in classical cylindrical scan, in order to reduce the computational effort and simplify the mechanical scanning. Numerical results assessing the effectiveness of the proposed technique are shown.