Visualization of radiated emission sources on a wire using far field amplitude data

In order to mitigate the emission radiated from electrical equipment, emission source finding methods must be studied. In this regard, the finding method utilizing the CISPR (International Special Committee on Radio Interference) emission measurement system, which uses only electric field amplitude data, has been proposed. Until now, this method has been applied to a few point sources; however, the general applicability to continuously distributed sources has not been revealed. In this paper, we present a new approach for which a new index is defined. This is the ratio of the estimated current amplitude to norm (the deviation between the estimated electric field amplitude and the measured value). By mapping this index distribution, calculated from random initial values in the optimization, the sources distribution can be visualized. In order to experimentally verify this effectiveness, a metallic wire in a semi-anechoic chamber was used. As a result, the distributed sources were visualized and the maximum current position was estimated within 0.21 m at 150 MHz. This was also verified in computer simulations through the moment method. Consequently, it is revealed that the applicability of this method is greatly improved by the presented approach.