Raising accuracy in the finding of radiated emission sources utilizing theCISPR emission measurement system

In order to mitigate the emission radiated from electrical equipment, emiss ion source finding methods need to be-studied. In this regard, the finding method utilizing CISPR emission measurement system, which uses only amplitu de data, has been proposed. However, there were some problems related to ca lculation convergence and dependence on initial source positions, as a resu lt of which the finding accuracy decreases in some cases. In this paper, it is shown that the finding accuracy in this method is greatly raised when t he calculation convergence is improved by optimizing Marquardt's constant, and the estimated sources are initially given at the optimum positions by t aking into account the deviation (Norm) between the measured electric field and the estimated one. In order to experimentally verify this finding, unk nown sources were estimated by using electric field data measured at a dist ance of 3 m in a semianechoic chamber, where two simulated emission sources were placed 0.4 m apart. Accurate estimated values were obtained, namely, a position estimation deviation of 0.09 m and an amplitude estimation devia tion of 0.29 dB at 500 MHz. Additionally, the finding accuracy is raised by adding the directivity of the source and the receiving antenna. Furthermor e, results in a fully anechoic chamber, in which the floor is covered with an electric wave absorber, show good; finding accuracy, equivalent to that in a semianechoic chamber. (C) 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(6): 50-59, 2001.