common mode current

When cables become the culprit in radiated emissions failures, an RF current probe can catch what near-field probes miss. This installment of EMC Bench Notes walks through measurement technique, transfer impedance math, and a downloadable E-field calculator for pass/fail estimation.

When testing EMI performance, substituting real loads with "equivalent" resistors can mislead you by up to 20dB—enough to turn a passing design into a costly failure. This practical guide demonstrates why fans, motors, and other non-linear loads behave dramatically differently than resistors, and why authentic testing matters for accurate results.