In communications and electronic engineering, a transmission line is a specialized cable or other structure designed to conduct radio frequency alternating current, ie currents with a sufficiently high frequency so that its wave nature is taken into account. Transmission lines are used for such purposes as the connection of radio transmitters and receivers with their antennas, distribution of cable television signals, trunk lines that route calls between telephone switching centers, computer network connections and computer data buses Of high speed.
This article covers the transmission line of two conductors, such as parallel line (ladder line), coaxial cable, band line and microstrip. Some sources also refer to waveguide, dielectric waveguide, and even fiber optics as a transmission line, however these lines require different analytical techniques and therefore are not covered by this article; see Waveguide (electromagnetism).