An investigation of the accuracy of far-field radiation patterns determined from near-field measurements

Abstract : The results reported show that far-field antenna patterns determined on the near-field range are as accurate as those determined on a far-field range. The patterns of a single plane, monopulse antenna, operated at 5.45 GHz were measured on a near-field range and two different far-field ranges, and detailed comparisons were made. The results of a computer-aided simulation study to determine the effects of various near-field measurement errors on the far-field patterns are also described. It was found that some near-field parameters are relatively critical; point source reflections are very deleterious. Far-field accuracy was found to be surprisingly insensitive to many near-field parameters. Comparisons of near-field and far-field techniques indicate several additional, non-technical, advantages of the near-field approach. Recommendations are made for future work to demonstrate the near-field technique on phased array antennas, and to improve the data processing procedures so as to increase the resolution of far-field patterns obtained from near-field measurements. (Author)