What is a Transmission Medium?
A transmission medium refers to a cable or radio wave equipment connecting customer premises equipment to switching equipment in a computer room or between two pieces of switching equipment. Transmission media are the most time consuming and costly project in telecommunications network infrastructure. Besides air acting as a transmission medium for radio communication, transmission media for telecommunications generally include copper wires and fiber optic cables. Copper wires are divided into a balanced line of twisted pair cable and an unbalanced line of coaxial cable. Based on their locations, transmission media are divided into the following: underground and overhead transmission lines, submarine cables, radio towers, antennas, guided wave ducts, and satellites.
In the early days of telecommunications, physical transmission media were open copper wires strung along power poles and on wooden loads and insulators. Today, copper wires have been replaced by fiber optic cables in both international and long distance networks. However, Internet access in Taiwan is still dominated by connections using plastic-insulated copper cables. In recent years, in order to increase broadband penetration, there has been widespread deployment of fiber optic networks and/or fiber-to-the-home. In addition, mobile phone base stations and antennas can be seen everywhere.