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Home > Mall Dynamic > What IS Coaxial Cable? Coaxial Cable Knowledge
Coaxial cable is a common type of cable used to transmit signals. It consists of an inner conductor, an insulating layer, an outer conductor and an outer insulating layer. The inner conductor is a wire, usually copper or aluminum, in a concentric position. It is wrapped in insulation to prevent signal leakage and electromagnetic interference. The outer conductor is a layer of metal mesh or foil over an insulating layer that acts as a shield. The outermost layer is an insulating layer that protects the cable from the external environment. This article will explain in detail what is coaxial cable, and the history of coaxial cable use
The development of coaxial cable is mainly divided into four generations: the first generation is the mid-19th century began to use polyethylene material as a solid core insulation medium; The second generation is the use of chemical foam PE material as insulation medium;
The third generation is PE material in the longitudinal hole of the root core as the insulating medium; The fourth generation is the use of physical foam PE material as an insulating medium. Coaxial cable according to the structure can be divided into: leakage coaxial cable, multi-core coaxial cable,
fine diameter coaxial cable, composite coaxial cable.
The coaxial cable industry has experienced a series of changes. As the global electronics industry entered its peak in 2000, as part of the electronics industry, the coaxial cable market size also reached its historical peak. In the following three years, as the global economic growth rate entered the trough,
the coaxial cable industry also entered the downturn with the contraction of downstream demand, until the second half of 2003 did not show signs of recovery. Since 2004, the global coaxial cable industry has entered a new round of growth. With the continuous expansion of mobile communication signal coverage,
the expansion of base stations, and the continuous improvement of mobile signal requirements in transportation, energy, medical and other fields, the market development prospects of the global RF coaxial cable industry are still promising.
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.
Coaxial cable can be divided into two basic types, baseband coaxial cable and broadband coaxial cable.
The shield layer of baseband coaxial cable is usually made of copper mesh structure, and its characteristic impedance is 50Ω. The cable is used to transmit digital signals, and the commonly used models are generally RG-8(thick cable) and RG-58(thin cable).
The most intuitive difference between thick and thin cables is the difference in cable diameter. Thick cable is suitable for relatively large local network, its standard distance is long, high reliability; However, the coarse cable network must install transceiver and transceiver cable, which is difficult to install,
so the overall cost is high. On the contrary, thin cables are simpler and less expensive; However, due to the need to cut off the cable during the installation process, it is easy to produce hidden dangers of poor contact when there are more connectors.
Whether the network is connected using thick or thin cables, the fault point often affects all the machines on the entire cable, and the diagnosis and repair of the fault is troublesome. Therefore, the baseband coaxial cable has been gradually replaced by unshielded twisted pair or optical cable.
The shield layer of broadband coaxial cable is usually stamped with aluminum, and its characteristic impedance is 75Ω. Commonly used to transmit analog signals, this cable, commonly known as RG-59,
is the standard transmission cable used in cable television networks and can transmit multiple TV signals simultaneously in a single cable. Broadband coaxial cable can also be used as a transmission medium for some computer networks.
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