A comparison of the contributions of common-mode and differential-mode currents in radiated emissions

It is shown that radiated emissions due to common-mode currents on printed circuit board lands can greatly exceed those due to differential-mode currents. It is concluded that predictions of radiated emissions based solely on differential-mode (transmission line) currents can bear little, if any, resemblance to actual measured emissions. Therefore, radiated emission prediction models that use only differential-mode (transmission-line) currents and ignore common-mode (antenna) currents are not adequate for the prediction of radiated emissions from printed circuit boards (as well as cables)