10.2.5 Advantages And Disadvantages Of Copper Transmission Lines

Copper-based transmission media have been used for as long as electronic communications systems have been in existence and are based on proven technologies and can be installed at low cost. They have the additional advantages of being able to carry high powers and are easy to use, join, and terminate.

Despite being easy to use and install, copper-based transmission media are very heavy when deployed in large numbers in cable ducts. They also induce current and radiate easily, which means that they suffer from significant crosstalk and interference from RF sources along the path. They also have large losses when used over more than short distances. Both of these problems can be alleviated by the use of shielding, but that makes the cables even heavier and more expensive to install. Transmission quality is also reduced for high data rates by the high-frequency limitations of copper cables.

These disadvantages can generally be accommodated for short distances and copper cables are still preferred for local area networks. The problems become significant, however, for medium-distance to long-distance communications requiring high bandwidth. Copper cables are now rarely used for these applications due to the expense associated with providing a large number of cables and the many repeaters required. The preferred long-distance transmission medium is based on optical-fiber technology.

As operating frequencies and bandwidth requirements increase, and as transmission distances extend into tens or hundreds of kilometers, the limitations of copper-based media become increasingly significant. These constraints have led to the widespread adoption of hollow metallic waveguides at microwave frequencies and optical fiber at very high data rates and long distances, which are examined in the following sections.