Coaxial Cable :: Networks Telecommunications

IntroductionCoaxial demarcation is an electrical occupation consisting of a round conducting wire, surrounded by an insulating spacer, surrounded by a cylindrical conducting sheath, usually surrounded by a final insulating layer. It is apply as a high-frequency transmission line to carry a high-frequency or broadband signal. Sometimes DC power (called bias) is added to the signal to supply the equipment at the other end, as in direct broadcast satellite receivers. Because the electromagnetic field carrying the signal exists (ideally) only in the space between the inside and outer conductors, it cannot interfere with or suffer interference from external electromagnetic fields.Coaxial stemmas may be rigid or flexible. Rigid types piss a solid sheath, while flexible types have a tissue sheath, both usually of thin copper wire. The inner insulator, also called the dielectric, has a significant effect on the cables properties, such as its characteristic resistor and its attenuatio n. The dielectric may be solid or perforated with tenor spaces. Connections to the ends of homocentric cables ar usually made with RF consociateors.Radio-grade flexible concentrical cable.A outer plastic sheathB copper blanketC inner dielectric insulatorD copper affectionThere are two types of coaxial cables1.Thinnet2.Thicknet ThinnetAlso known as Thin Ethernet or Thinnet, 10BASE-2 is an IEEE standard for baseband Ethernet at 10MBps over thick coaxial cable. 10Base2 has a maximum distance of 185 meters. Thin Ethernet is five millimeters in diameter and used to connect machines up to 1,000 feet apart.Thinnet (thin Ethernet) is an incarnation of the Ethernet standard in which coaxial cables are used in a LAN (local-area network) configuration to connect computers together. A Thinnet setup is capable of transmitting data at a rate of 10Mbps (megabits per second). It is also cheaper and easier to install than Thicknet.The first variation on the pilot variety of Ethernet was si mply to use a thinner coaxial cable and relax the constraints on how and where transceivers can connect. 10BASE-2 does this with coaxial cable that looks just similar the cable used for receiving cable television or hooking up a television set to an antenna. The only difference in the cable itself is the impedance rating. A television cable is rated at 75 ohms and a 10BASE-2 cable is rated at 50 ohms. In a pinch, a junior-grade length of one can be substituted for the other. The connectors used in 10BASE-2 are called BNC connectors for Berkeley Nucleonics Co. they were originally used in nuclear physics.