A Nonredundant Near-Field to Far-Field Transformation with Spherical Spiral Scanning for Nonspherical Antennas

ABSTRACT

A fast and accurate near-field – far-field transformation technique with spherical spiral scanning tailored for nonspherical antennas, i.e., radiating systems with two dimensions very different from the third one, is developed in this paper. To this end, an antenna with one or two predominant dimensions (e.g., base station antennas and reflectarrays) is no longer considered as enclosed in a sphere, but in a prolate or oblate ellipsoid, respectively, thus allowing a remarkable reduction of the number of the near-field data to be acquired. Moreover, these source modellings remain quite general and contain the spherical one as particular case. Some numerical simulations, assessing the accuracy of the far-field reconstruction process and its robustness with respect to random errors affecting the data, are reported.