Input/Output Cable

In reality, most devices require input and/or output connections, which may be power lines or signal and control lines. The cables that provide these connections can act as antennas, capable of picking up interference, or they can radiate it (Figure 2). Cables or wires that pass through a device's enclosure can introduce electrical noise that radiates internally to other wires and circuits. Likewise, it can provide a path to the outside from any noise generated internally, which can also be radiated and may in turn adversely affect other equipment.

1. Interference can enter a device directly through wiring (conducted interference).

2. Radiated interference can propagate directly to affected equipment.

3. Interference can leave the EMI source through the cable and subsequently radiate from the cable to the affected equipment.

4. Interference can be radiated from the EMI source and then received through the cables entering the affected equipment.