An Effective NF-FF Transformation Technique With Planar Spiral Scanning Tailored For Quasi-Planar Antennas

An effective probe compensated near-field—far-field transformation technique with planar spiral scanning is developed in this paper. It makes use of an ellipsoidal modelling of the source, instead of the previously adopted spherical one. Such a modelling, tailored for quasi-planar antennas, allows one to consider measurement planes at a distance smaller than one half the antenna maximum size, thus reducing the error related to the truncation of the scanning surface. Moreover, it is quite general, containing the spherical modelling as particular case, and reduces significantly the number of the needed near-field data when dealing with quasi planar antennas. Some numerical tests, assessing the accuracy of the technique and its stability with respect to random errors affecting the data, are reported.