Data Communication

In the past decades, the telecommunication industry has developed rapidly. A wide selection of transmission media have been applied. Fiber optic cables are widely used in today’s network. It seems that copper cables are out of fashion. However, there are still many advantages of using copper cables. This passage is going to introduce copper cable from the aspect of types and applications.

Before we get to know copper cable, let’s learn something basic about copper. Copper is a kind of electrical conductor which has the highest electrical conductivity rating of all non-precious metals. Therefore, copper is used in many categories of electrical wiring which is the most important market for the copper industry. And copper wire is used in power generation, power transmission, power distribution, telecommunication, electronic circuity and countless types of electrical equipment.

A copper cable consists of two or more copper wires running side by side and bonded, twisted or braided together to form a single assembly. And copper wires in a cable may be bare or they may be plated to reduce oxidation with a thin layer of another metal, most often tin but sometimes gold or silver. It is not difficult to find that many features of copper cable are related to the nature of copper, such as high tensile strength, high ductility, good creep resistance, good corrosion resistance, low coefficient of thermal expansion, high thermal conductivity, good flexibility and so on.

This part will show twisted pair cable and coaxial cable which are designed to inhibit electromagnetic interference, prevent radiation of signals, and to provide transmission lines with defined characteristics.

Twisted pair cable is a type of cable in which two conductors of a single circuit are twisted together for the purposes of canceling out electromagnetic interference (EMI) from external sources. It is often used in data networks for short and medium length connections due to its relatively lower cost compared to optical fiber. And it can divided into two kinds: UTP and STP. UTP for Unshielded Twisted Pair, no shielding; while STP for Shielded Twisted Pair, having a metal shield around each twisted pair, all pairs together are in the cable covered by insulation. The figure below shows the differences between UTP and STP.

UTP cable is the primary cable type for telephone systems. And it is also used increasingly in video application, mainly in security cameras. While STP cable is often used in business installations such as connecting home and many business computers to the telephone company. Both UTP and STP cables are found in many Ethernet networks. For example, Cat 5e UTP cable with 100-MHz bandwidth is common for current LANs; and Cat 6 UTP cable with 250 MHz bandwidth and Cat 7 STP cable with 600 MHz bandwidth are commonly used for 10GBASE-T Ethernet.

Coaxial cable is a type of cable that has an inner conductor surrounded by a tubular insulating layer, and outside the layer, there is a tubular conducting shield surrounded by the plastic jacket (shown as the figure below). Coaxial cable is extensively used in mainframe computer systems and it is the first type of major cable used for Local Area Networks (LAN). Common applications for coaxial cable today include computer network (Internet) and instrumentation data connections, video and CATV distribution, RF and microwave transmission, and feedlines connecting radio transmitters and receivers with their antennas.

In the introduction to twisted pair cable, we speak of Cat 5 and Cat 6 cables. In fact, they belong to Ethernet cable which is one of the most popular forms of network cable used on wired networks and Ethernet networks. And Ethernet cable is commonly used to connect devices on local area networks such as PCs, routers and switches. Although Ethernet cable is limited on the transmission distance compared with fiber optic cable, it is still being widely used in short distance applications providing cost-effective and easy-to-manage solutions. In addition, Ethernet cables are keeping upgrading in these years, from Cat 5, Cat 5e, Cat 6 and Cat 7. And even Cat 8, which is said to provide 40 Gigabit Ethernet, will be applied in data centers. Ethernet cable is gradually developed to support higher data rate and longer transmission distances. Applications like G.Fast, which use copper cable for “last mile” transmission, are also becoming popular. In many houses, Ethernet cables are still their options during home network deployment.

Though fiber optic cable is popular among many data centers which need high speed transmission data rate, copper cable still plays an important role in wired networks. Believe it or not, with the development of technology, copper cable will have a better and better performance in network cabling.