Nonredundant near-to far-field transformation with spherical scanning suitable for an offset mounted quasi-planar antenna

A nonredundant near field - far field (NF–FF) transformation technique with spherical scanning for offset mounted quasi-planar antennas is here proposed. Unlike the classical NF–FF transformation, it allows the reconstruction of the far field radiated by the antenna under test (AUT) from a minimum number of NF data, which does not change when the AUT is mounted in an offset configuration. This interesting result is obtained by properly exploiting the nonredundant sampling representation of the electromagnetic field and considering the AUT as enclosed in an oblate ellipsoid. An optimal sampling interpolation algorithm is applied to accurately recover the NF data required by the classical (NF–FF) transformation from the nonredundant ones. It is so possible to get a remarkable measurement time saving. Some numerical results assessing the accuracy of the proposed technique and its stability with respect to random errors affecting the NF data are shown.