Coaxial cable outer diameter (OD) is defined by the measurement of which component?

• A. Jacket
• B. Outer metallic conductor
• C. Dielectric
• D. Center conductor

Answer: (B)

The outer diameter of coaxial cable is defined by the measurement of the outer metallic conductor—the shield. This outer conductor forms the external boundary that defines the cable’s electrical geometry and interfaces with connectors and fittings. The impedance of the cable is set by the relationship between the center conductor and the inner surface of this outer conductor within the dielectric, so the critical dimension for OD is the shield’s outer surface. The dielectric and center conductor are inside this boundary, and the jacket sits outside the shield as a protective layer; while it can affect the overall physical size, it does not set the defining external dimension used for OD.