Copyright Goodheart-Willcox Co., Inc. 61 Chapter 2 Network Media—Copper-Core Cable Coaxial Applications You may encounter coaxial cable being used from an antenna or satellite dish to a network system or as a network backbone. A media converter or bridge device is used to convert the signal from coaxial cable to a twisted-pair cable. Video applications, such as cable and satellite TV, typically use coaxial cable “RG” as the medium to carry their high-frequency signals rather than twisted-pair cable. High-frequency signals are aff ected by twists in cables. When a video or audio signal is transmitted over a twisted conductor, the maximum length the signal can travel is drastically reduced. Th e twist in the cable causes an electronic characteristic known as induction, which will distort the high-frequency signal. Th e distorted signal results in a distorted image or audio at the destination. Areas that are prewired with coaxial cable may be used as a part of a twisted- pair cabled network. D-Link, NETGEAR, and several other manufacturers have start- er kits for using existing coax. Th e kit includes media bridges, or media converters, which have an F-type connection for the coaxial cable and an RJ-45 connection for twisted-pair cable. Coaxial Cable Classifi cations Th ere are several classifi cations of network coaxial cable. Figure 2-16 lists some of the most common types of coaxial cable and their applications. Th e three most common coaxial cable types that have been used for networking are RG-6, RG-8 (thicknet), and RG-58 (thinnet). 2.1 NET Figure 2-16 Coaxial cable types and their applications. Goodheart-Willcox Publisher Cable Common Name Impedance Actual Size in Diameter Description RG-6 Broadband 75 Ω 0.332 Used for cable TV. RG-8 Thicknet 50 Ω 0.405 Used for Ethernet networks. RG-11 Thick coax 75 Ω 0.475 Used for cable TV trunk lines. RG-58 Thinnet 50 Ω 0.195 Used for Ethernet networks. RG-59 CATV 75 Ω 0.242 Used for cable TV and sometimes used for ARCnet. RG-62 Baseband 93 Ω 0.249 Used for ARCnet. RG-6 RG-6 is the standard for cable television (CATV) systems and satellite systems, re- placing other types of cable such as RG-59 for new installations. RG-6 in television applications typically use F-type connectors. RG-6 is often marked as RG-6/U and RG-6/UQ. Th e U represents universal specifi cation, which is an old military grade standard. Th e Q in RG-6/UQ represents Quad for quad shielding. Quad shielding has four layers of shielding rather than the typical two layers like that in RG-6/U. Coaxial cable used for television is not acceptable for use as a network cable. Its characteristics work well for television transmission but will cause problems if used for computer networks. Tech Tip The EIA/TIA 570 residential communication standard recommends RG-6 for new residential installations.