In shielded cables, what is the shield typically made of?

In shielded cables, what is the shield typically made of?

• A. Dielectric oil
• B. Insulating plastic
• C. Air gap
• D. A surrounding conductive foil or braid

Answer: (D)

The shielding in shielded cables is a conductive barrier that surrounds the inner conductors. This shield is typically a surrounding conductive foil or braid (or both), which acts like a Faraday cage to block external electromagnetic interference and to provide a low-impedance return path to ground. That metallic layer is what actually protects the signal from picking up noise and also helps reduce crosstalk between wires. Dielectric oil is used in some specialty cables as a filling fluid to insulate and fill voids, but it isn’t a shield. Insulating plastic serves as the dielectric or jacket material around the conductors, not as a shielding layer. An air gap can influence dielectric properties and spacing, but it does not function as the shield itself.

The shielding in shielded cables is a conductive barrier that surrounds the inner conductors. This shield is typically a surrounding conductive foil or braid (or both), which acts like a Faraday cage to block external electromagnetic interference and to provide a low-impedance return path to ground. That metallic layer is what actually protects the signal from picking up noise and also helps reduce crosstalk between wires.

Dielectric oil is used in some specialty cables as a filling fluid to insulate and fill voids, but it isn’t a shield. Insulating plastic serves as the dielectric or jacket material around the conductors, not as a shielding layer. An air gap can influence dielectric properties and spacing, but it does not function as the shield itself.