Comparative investigation of methods to reduce truncation errors in partial spherical near-field antenna measurements

Abstract

This paper presents a comparative investigation of two different but highly suitable techniques for the accurate determination of the full sphere pattern of an antenna from truncated spherical near field measurements. The first approach is based on an iterative procedure which exploits the band-limitedness properties of the radiated field to correctly reconstruct the full sphere data [1]. The second approach was first described in [2] and is based on determining a set of equivalent currents that radiate the same pattern in the known area and thus extrapolate the unknown fields in the truncated area. The comparative study is performed on actual measured near-field data to investigate the effectiveness of each technique in realistic spherical near field antenna measurement scenarios. © 2012 IEEE

Improvement of antenna measurement results at low frequencies by using post-processing techniques

“…From the equivalent currents the field on the full measured surface can be evaluated. This process mitigates the pattern error due to scan truncation that otherwise would show as a ripple due to the zero padding of the NF data in the traditional NF-FF transformation [27].…”

Valid angle criterion and radiation pattern estimation via singular value decomposition for planar scanning

“…As a consequence, errors in the far-field evaluation (truncation error) are introduced which clearly depends on the extension of the observation domain, the antenna's size and the distance between them. To limit the effect of a finite measurement aperture, many authors have investigated methods for improving the accuracy of the calculated far-field pattern without additional measurements [3,4]. One idea is to use near-field measurements to reconstruct equivalent currents residing over a fictitious surface by inverting the pertinent integral equation and from this compute the radiation pattern [3].…”