Coaxial cables are divided into four layers from the inside out: central copper wire (single solid wire or stranded wire), plastic insulator, reticular conductive layer and wire outer layer. The central copper wire and reticular conductive layer form a current loop. Because the central copper wire and reticular conductive layer are coaxial.
Coaxial cables conduct alternating current (ac) rather than direct current (dc), meaning that the current direction reverses several times per second.
If you use ordinary wire transmission of high frequency current, this wire is the same as a root to launch radio antenna, the effect is the loss of signal power, makes the received signal strength decreases.
Coaxial cable is designed to solve this problem. The radio from the central wire is isolated by the reticular layer, which can control the radio by grounding it.
Coaxial cable is also a problem, that is, if the cable is a section of the larger extrusion or distortion, so the distance between the center wire and mesh conductive layer is not consistent, which can cause internal radio waves will be reflected back to the signal source. This effect reduces the power of the received signal. To overcome this problem, a layer of plastic insulator is added between the central wire and the reticular conductive layer to ensure that the distance between them is consistent. This has also resulted in the cable being rigid and not easily bent.