Residential Broadband, Second Edition

Metallic Transmission Media

This section presents some physical characteristics of metallic wiring familiar to consumers, specifically phone wire and coaxial cable used in cable TV. Fiber transmission and wireless media will be discussed later in this chapter.

Copper wiring is a ubiquitous, well-understood medium. It comes in two broad classes, for this discussion: phone wire and coaxial cable. Both classes have variants, but each has been standardized on a few options. Phone wire consists of two thin copper wires, which are twisted in a helical pattern around each other. The twisted pair is wrapped in an insulating cover of plastic, rubber, or lacquer. At its limit, phone wire can transmit 1 MHz for a distance of roughly 3 miles, or 30 MHz ...