Method for Estimating Countermeasure Effect of CMF on Radiated Emission via Cables by CM Current

A method for estimating the countermeasure effect using a common-mode filter (hereafter referred to as CMF effect) is proposed, based on the concept of disturbance power propagation. The method was applied to the radiated electric field (hereafter referred to as E-field) strength from cables, and analysis using the chain parameter matrix showed that the CMF effect on the E-field could be estimated from the CMF effect on the CM (Common-Mode) current at the cable input. A measurement using a test setup according to CISPR 25 indicated that the correlation coefficient between the CMF effect on the E-field and the CMF effect on the CM current was more than 0.97 in the frequency range from 31 to 239MHz. The CMF effect on the CM current was measured in a regular laboratory, and the correlation coefficient was more than 0.95. In addition, the CMF effect on the CM current was calculated using the chain parameter matrix, and the correlation coefficient was more than 0.94. These results showed that the proposed method can efficiently estimate the CMF effect on the E-field from an experiment in a regular laboratory and through calculation.