There are two ways of electromagnetic disturbance on cable: magnetic field coupling and electric field coupling
In the electromagnetic compatibility test of electronic equipment, many projects are carried out for the equipment's external tow cable. This is based on the effect of electromagnetic fields on electronic equipment, the main manifestation of which is the generation of an induced voltage on a long cable.
There are two ways to inject electromagnetic harassment energy into a cable. One is called magnetic field injection, so called because it uses electromagnetic induction to couple energy. The above image on the right shows how this works, similar to a transformer. The top left is a current caliper for injection of disturbance. There are two calipers, one for injection of disturbance and the other for monitoring the magnitude of injection of current.
The other method is called electric field injection, so called because it uses electric field coupling to inject disturbance energy into the cable. Specifically, energy is coupled to the cable through capacitors, as shown in the figure below. The injection device used is called a capacitive coupling clamp, as shown in the lower left figure. The coupling clamp is actually a metal plate that acts as one electrode of the capacitor, and the cable is clipped near this metal plate as another electrode of the capacitor.
Most commercial standards use the method of capacitor injection, military standard electromagnetic compatibility test GJB151, through mutual inductance coupling into the cable harassment voltage.