Which type of cable provides higher bandwidth and better protection against EMI than twisted-pair conductors?

• A. Coaxial cable
• B. Fiber optic cable
• C. Shielded twisted-pair cable
• D. Unshielded twisted-pair cable

Answer: (A)

High bandwidth and EMI protection come from how a cable is built. Coaxial cable has a central conductor, a dielectric insulator, and a metallic shield wrapped around it. That shield acts like a Faraday cage, substantially reducing external electromagnetic interference and preventing the signal from leaking out. With this shielding and a controlled impedance design, coax can carry higher-frequency signals more cleanly than unshielded twisted-pair, giving higher bandwidth over typical runs. Shielded twisted-pair does improve EMI protection versus unshielded, but it generally doesn’t achieve the same high-frequency performance as coax in many installations. Fiber optic would beat both in EMI immunity and bandwidth, but among these options, coaxial cable provides the best combination of higher bandwidth and EMI protection compared with twisted-pair.