The effect of cable terminations on EMI measurements

Abstract

The effects of using uncontrolled or undefined cable terminations during electromagnetic interference (EMI) measurements was investigated. Several different models are described along with corresponding measurements in order to illustrate how specific terminations can be used to achieve particular measurement goals. It is noted that until a well-defined method of terminating power and signal cables is introduced, the best the EMI test engineer can do is to be aware of the significance of common-mode terminations and try to avoid situations where the common-mode termination impedance is completely undefined or not repeatable.<>