The coaxial cable is divided into four layers from the inside to the outside: a central copper wire (single stranded solid wire or multiple stranded wire), a plastic insulator, a mesh conductive layer and a wire sheath. The central copper wire and the mesh conductive layer form a current loop. It is named because the central copper wire and the mesh conductive layer are coaxial.
The coaxial cable conducts alternating current instead of direct current, which means that the current direction is reversed several times per second.
If a high-frequency current is transmitted using a general wire, the wire will be equivalent to an antenna that emits radio to the outside. This effect loses power of the signal and reduces the received signal strength.
The coaxial cable is designed to solve this problem. The radio emitted by the center wire is isolated by a mesh-shaped conductive layer that can be grounded to control the emitted radio.
A problem with coaxial cable is that if a certain section of the cable is subjected to relatively large extrusion or distortion, the distance between the center wire and the mesh conductive layer is not consistent, which causes the internal radio waves to be Reflected back to the signal source. This effect reduces the signal power that can be received. To overcome this problem, a layer of plastic insulator is added between the center wire and the mesh conductive layer to ensure that the distance between them is consistent. This also causes the cable to be stiff and not easily bent.