  Accurate characterization of large-scale antenna arrays is growing in
importance and complexity for the fifth-generation (5G) and beyond systems, as
they feature more antenna elements and require increased overall performance.
The full 3D patterns of all antenna elements in the array need to be
characterized because they are in general different due to construction
inaccuracy, coupling, antenna array's asymmetry, etc. The effective aperture
distribution function (EADF) can provide an analytic description of an antenna
array based on a full-sphere measurement of the array in an anechoic chamber.
However, as the array aperture increases, denser spatial samples are needed for
EADF due to large distance offsets of array elements from the reference point
in the anechoic chamber, leading to a prohibitive measurement time and
increased complexity of EADF. In this paper, we present the EADF applied to
large-scale arrays and highlight issues caused by the large array aperture. To
overcome the issues, an enhanced EADF is proposed with a low complexity that is
intrinsically determined by the characteristic of each array element rather
than the array aperture. The enhanced EADF is validated using experimental
measurements conducted at 27-30 GHz frequency band with a relatively large
planar array.
