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

In order to mitigate the emission radiated from electrical equipment, emission source finding methods need to be studied. In this regard, the finding method utilizing CISPR emission measurement system, which uses only amplitude data, has been proposed. However, there were some problems related to calculation convergence and dependence on initial source positions, as a result 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 the calculation convergence is improved by optimizing Marquardt's constant, and the estimated sources are initially given at the optimum positions by taking into account the deviation (Norm) between the measured electric field and the estimated one. In order to experimentally verify this finding, unknown sources were estimated by using electric field data measured at a distance 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 deviation of 0.29 dB at 500 MHz. Additionally, the finding accuracy is raised by adding the directivity of the source and the receiving antenna. Furthermore, 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. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(6): 50–59, 2001