Working principle of coaxial cable

Working principle of coaxial cable

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Working principle of coaxial cable

The coaxial cable is divided into four layers from inside to outside: the central copper wire (single strand of solid wire or multi-strand stranded wire), the plastic insulator, the mesh conductive layer and the wire skin. The central copper wire and the network conductive layer form a current loop. It is named because of the coaxial relationship between the central copper wire and the network conductive layer.

Coaxial cables conduct alternating current rather than direct current, which means that the direction of the current is reversed several times per second.

If a regular wire is used to transmit high-frequency current, the wire acts as an antenna transmitting radio outward, and this effect consumes the power of the signal and reduces the strength of the received signal.

Coaxial cable is designed to solve this problem. The radio emitted from the central wire is isolated by a mesh conductive layer, which can be grounded to control the emitted radio.

Coaxial cable also has a problem, that is, if a section of the cable is relatively large extrusion or distortion, then the distance between the center wire and the mesh conductive layer is not consistent, which will cause 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 insulation is added between the central wire and the mesh conductive layer to ensure a consistent distance between them. This also causes the cable to be stiff and not easily bent.

The shielding material of coaxial cable is essentially improved on the external conductor, from the initial tubular outer conductor, in turn developed into a single braided, double metal. Although the tubular outer conductor has very good shielding performance, it is not easy to bend and is not convenient to use. The shielding efficiency of single-layer braid is the worst, and the transfer impedance of double-layer braid is 3 times less than that of one-layer braid, so the shielding effect of double-layer braid is greatly improved than that of single-layer braid. Major coaxial cable manufacturers are constantly improving the outer conductor structure of the cable to maintain its performance.

Post time: Sep-14-2023