Data post-processing and hardware architecture of electromagnetic near field scanner

Near-field scanning performed in close proximity to the tested object is an attractive measurement technique for the EMC compliant verification of the design of complex electronic devices since it may be simultaneously utilized for the estimation of radiation characteristics as well as for spatial and frequency localizations of electromagnetic interference sources. Specific requirements and key parameters of the measurement system to map electromagnetic fields, due to the tested object radiating an arbitrary but periodic emission, are enumerated to consider the applicability of various hardware architectures. Speed and accuracy issues of the scanning procedure are discussed. Two measurement set-ups for scanning either linear or nonlinear radiating objects together with the utilized field probes are described in detail. A scalar model of the field measurement over a planar surface is proposed to describe a non-ideal receiving behaviour of a field probe. Plane-wave back and forward propagation methods are presented to enhance spatial resolution of the recognized field sources and to predict field radiation in a near-field region of the tested object. Major systematic and statistical errors of the post-processings, defined for a finite set of data in the frequency domain superimposed by the measurement noise, are discussed.