Optimal far field estimation from near zone measurements

Abstract

The accurate determination of the field radiated by modern high-performance antennas is often accomplished by means of a near-field-far-field transformation technique (NF-FF), in order to exploit the advantages of an indoor, highly noiseless measurement setup. The objective of any NF-FF algorithm must be the optimal estimate of the far field, i.e. the estimate corresponding to the minimum reconstruction error compatible with the incomplete and corrupted measured data and the available information. The optimal NF-FF algorithm also minimizes the number of measurements and the computational effort, making it possible to account for the probe effect without additional computational complexity. Moreover, it should not be connected to a particular scanning surface, in order that positioning error can be easily accounted for. As an example, the evaluation of the far field of a planar array of 21*21 x-oriented electrical dipoles, in the z=0 plane, spaced lambda /2 apart and directed along x is considered.<>