Acquisition, reconstruction, and transformation of a spiral near-field scan

Abstract

The topic of non-redundant near-field sampling has received much attention in recent literature. However, a practical implementation has so far been elusive. This paper describes a first step toward such a practical implementation, where the practicality and generality are maximized at the expense of more acquired data points. Building on the theoretical work of faculty at the University of Salerno and University of Naples [1]-[17], the authors have acquired a set of near-field data using a spiral locus of sample points and, from those data, obtained the far-field patterns. In this paper, we discuss the acquisition system, the calculation and practical implementation of the spiral, the phase transformations, interpolations, and far-field transforms. We also present the resultant far-field patterns and compare them to patterns of the same antenna obtained using conventional near-field scanning. Qualitative results involving aperture back-projection are also given. We summarize our findings with a discussion of error, uncertainty, acquisition time, and processing time in this simplified approach to non-redundant sampling in a practical system.