It is composed-from the inside out-of an inner conductor, insulation, an outer conductor, and a sheath.
Inner conductor: Since signal attenuation is primarily caused by the resistance of the inner conductor, it significantly impacts signal transmission.
Insulation: Affects performance characteristics such as attenuation, impedance, and return loss.
Outer conductor: Serves as the return path and provides shielding.
Sheath: Protects the internal structure from mechanical damage and environmental factors (such as moisture and chemical corrosion). Taking coaxial cable as an example, structural parameters-such as inner conductor diameter, insulation outer diameter, and characteristic impedance-must comply with relevant standards.
Interference resistance is a core aspect of the design and application of low-voltage cables. Engineering projects require comprehensive consideration of factors such as the transmission environment, transmission method, installation quality, and system design.
Shielding effectiveness is a key metric for evaluating a cable's resistance to electromagnetic interference. The industry standard GA/T 1297-2021, *Security Cables*, uses "transfer impedance" to objectively assess shielding performance, specifying graded criteria based on different shielding techniques and materials.