Truncation-error reduction in 2D spherical/cylindrical near-field scanning

The spherical and cylindrical near-field (NF) antenna measurement techniques are an indispensable tool for the antenna community. NF samples are almost always collected over a truncated surface. Far-field (FF) values computed from truncated NF data suffer from truncation errors. In this paper, we introduce a new NF-to-FF transformation for two-dimensional cylindrical/spherical scanning that significantly reduces truncation errors. After examining the limitations of the traditional multipole-based expansion of truncated scan data, we consider an alternative expansion based on Slepian functions and show how FF values can be extracted from the resulting expansion coefficients.