Nature and Classification of Disturbances
Electromagnetic measurements

Disturbances generated by or experienced by equipment can have multiple sources and exhibit complex propagation modes:

• by conduction through cables connected to the equipment;

• by direct radiation on chassis, circuit boards, or internal wiring;

• through various types of coupling involving the two previous modes: cable-to-cable coupling, common-impedance coupling.

To better understand the possible coupling mechanisms, Figure2 illustrates the various types of access points for a given device.