Coaxial cable is a two-conductor transmission line with an outer metal tube or a central conductor surrounded by a mesh shield.
What is a Coaxial Cable Used For?
The inner conductor is supported by a kind of dielectric insulation, which can be solid, expanded plastic or semi-solid. It supports semi-solid polyethylene discs, helical tapes, or helically wrapped plastic tapes.
In some designs, insulating beads, support pins, or periodically bent plastic tubes are used. The important feature of the coaxial cable is that it has a shielded structure.
The electromagnetic field associated with each Coaxial unit is nominally limited by the space between the inner and outer conductors.
As the alternating current is condensed with increasing frequency in the outer conductor, a Coaxial unit is a self-shielded transmission line whose shield is increased at higher frequencies.
Unprotected lines such as multi-pair cable share the gap of electromagnetic fields. That is, for an equivalent transmission loss, pairs take up less space than Coaxial ones.
The main use of this cable is the transmission of high-frequency broadband signals.
These cables use the frequency of sound very little because their protection properties are poor. They are also more expensive than twisted pairs with the same transmission loss.
History
In the 1930s, it served as the transport of high-frequency electrical signals with two concentric conductors, called the central, responsible for carrying information, and the return of a tubular appearance, ground reference, and currents, called lattice or protection.
Between the two is an insulating layer called a dielectric, the properties of which depend mainly on the quality of the cable. The whole set is usually protected by an insulating cover.
Due to the increasingly higher frequencies and the need to digitize transmissions, its use in recent years has been replaced by fiber optics with much higher bandwidth, especially for distances greater than a few kilometers.
Properties
There are three general types of Coaxial cables, flexible, semi-rigid, and rigid for different applications.
In general, the harder the cable, the electrical properties will be more stable and predictable. It is important that the loss in a cable is low, as the loss in a transmission line increases approximately with the frequency rating.
Also, physical and electrical irregularities, especially if they are periodic, should be kept to a minimum or coaxial transmission loss at certain frequencies will be very high.
Its structure changes the design choice, affects the size flexibility and the cable loses its properties.
It consists of a coaxial cable, an insulator, a braided metal shield, and a core of copper wire surrounded by an outer sheath.
Protection relates to mesh or other material surrounding metal mesh or cables.
The shield protects the transmitted data, absorbs noise, so it doesn’t pass through the cable and no data corruption. The cable containing the insulating layer and the braided metal protection layer is called double-shielded cable.
There are four types of protection for large parasites. This shield consists of two layers of insulation and two layers of metal protection.
The core of this cable, copper wire, carries electronic signals that make up the information. It is a dielectric insulation layer that surrounds the core and separates it from wire mesh.
Braided wire mesh acts as a mass and helps maintain healthy data transmission by protecting the core from electrical noise and distortion from adjacent wires.
In addition to the core being protected, if a short circuit occurs, noise or signals pass through the copper wire.
A short circuit occurs when two wires or a wire and a ground contact. In this case, it causes direct current flow in an undesirable path.
In the case of a common electrical installation, a short circuit causes a spark and blown fuse or circuit breaker.
In electronic devices using low voltage, the effect is less and almost imperceptible.
These low voltage short circuits cause the device to malfunction and cause the loss of the transferred data.
To prevent possible electric shock, a non-conductive outer sheath, usually made of rubber, teflon or plastic, surrounds the entire cable to provide protection.
Coaxial cable is more resistant to interference and attenuation than twisted-pair cable, so they were more preferred.
Wire mesh prevents lost electronic signals, so it does not affect data sent from the internal cable.
Therefore, the coaxial cable is a good choice to reliably support large amounts of data with a simple system for long distances.
In coaxial cables, areas arising from the currents inside and outside cancel out.
Types
There are multiple types of coaxial cables, each with a different diameter and impedance.
The coaxial cable is normally not affected by external interference and can reach high transmission speeds over long distances.
Therefore, it is used in Broadband communication networks (television cable) and baseband cables (Ethernet).
The type of cable to be used depends on the position of the cable.
Coaxial cables can be of two types:
Polyvinyl Chloride (PVC): It is a type of plastic used in most coaxial cable types to create cable insulation and a protective sheath. PVC coaxial cable is flexible and can be easily installed anywhere. However, when it burns, toxic gases are released.Plenum: It contains special materials in insulation and a cable plug. These materials are fire-resistant and produce a minimum amount of smoke. Also, this reduces toxic fumes. However, plenum wiring is more expensive and less flexible than PVC.Types of Cable
The main feature of the RG-58 family is a central copper wire. RG-58/U, RG-58 A/U is RG-59, RG-6, and RG-62 for Broadband transmission (TV).
Where is it Used?
Coaxial cable is used between antenna and television, cable television, internet networks, radio broadcasts, video signal distribution, data transmission networks such as Ethernet in 10BASE2 and 10BASE5 old versions, and long-distance telephone networks and submarine cables.
Before largely fiber optics were used in both terrestrial and submarine telecommunications networks, coaxial cable was widely used in analog telephone transmission systems based on frequency division multiplexing (FDM), where transmission capacities were obtained from more than 10,000 audio circuits.
In addition, more than 7,000 64 kbps channels were transmitted in digital transmission systems based on time-division multiplexing (TDM).
The cable used for these long-distance transmission purposes had to have a different structure than that used in LAN network applications because it had to be protected against stress and pressure stress since it was installed embedded, so apart from the corresponding ones, the insulators had outer steel reinforcement.
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