Coaxial cables are divided into four layers from the inside out: central copper wire (single stranded solid wire or multi stranded wire), plastic insulation, mesh conductive layer, and wire sheath. The central copper wire and the mesh conductive layer form a current circuit. It is named after the coaxial relationship between the central copper wire and the mesh conductive layer.
Coaxial cables conduct alternating current instead of direct current, which means that there are several reversals in the direction of the current every second.
If a regular wire is used to transmit high-frequency current, this type of wire will act as an antenna emitting radio outwards, which loses the power of the signal and reduces the strength of the received signal.
The design of coaxial cables is precisely to solve this problem. The radio emitted by the central wire is isolated by a mesh conductive layer, which can control the emitted radio through grounding.
There is also a problem with coaxial cables, which is that if a certain section of the cable undergoes significant compression or distortion, the distance between the central wire and the mesh conductive layer is not consistent, which can cause internal radio waves to be reflected back to the signal sending source. This effect reduces the acceptable signal power. To overcome this problem, a layer of plastic insulation is added between the central wire and the mesh conductive layer to ensure a consistent distance between them. This also creates the characteristic of this type of cable being relatively rigid and not easily bent.
The shielding material of coaxial cables is essentially an improvement on the external conductor, evolving from the initial tubular external conductor to single-layer braided and double-layer metal. Although the tubular outer conductor has excellent shielding performance, it is not easy to bend and is not convenient to use. The shielding efficiency of single-layer weaving is the worst, with the transfer impedance of double-layer weaving reduced by three times compared to single-layer weaving. It can be seen that the shielding effect of double-layer weaving has greatly improved compared to single-layer weaving. Major coaxial cable manufacturers are continuously improving the outer conductor structure of cables to maintain their performance