Which of the following is NOT an EMI mitigation technique?

• A. Proper grounding
• B. Shielding
• C. Using long, unshielded cables
• D. EMI filters

Answer: (C)

EMI mitigation focuses on preventing interference from entering or leaving a system and preserving signal integrity. Grounding gives a low-impedance return path and stabilizes reference levels, helping to shrink unwanted voltage differences that can carry noise. Shielding adds a conductive barrier around cables or components to block external electromagnetic fields from reaching the signal and to keep internally generated noise from radiating outward. EMI filters suppress high-frequency components at entry points, so conducted noise is attenuated before it can affect the circuit or be emitted.

Using long, unshielded cables is not a mitigation technique because they behave like antennas. They readily pick up EMI from nearby equipment and broadcasts, and without shielding they also radiate noise, increasing coupling into and out of the system. The longer the cable, the more susceptible it becomes to interference and the greater the potential for signal degradation and data errors.