Fast and Accurate Far-Field Prediction by Using a Reduced Number of Bipolar Measurements

This letter gives the experimental assessment of a near-to-far-field transformation (NTFFT) technique allowing the fast and accurate reconstruction of the antenna far field from a nonredundant, i.e., minimum number of near-field (NF) data collected through a bipolar scanning. Such a NTFFT relies on a nonredundant sampling representation of the voltage detected by the scanning probe, attained by shaping the antenna with an oblate ellipsoid, a model suitable to deal with quasi-planar antennas, as typically are the measured ones in a planar NF facility. The NF data necessary to execute the traditional plane-rectangular NTFFT are then effectively recovered from the acquired (nonredundant) bipolar ones by exploiting a 2-D optimal sampling interpolation formula. This makes possible to achieve a remarkable acquisition time saving, which is a very relevant outcome, because this time is nowadays much greater than that needed to carry out the NTFFT.