Transmission-line inductors:

At the radio frequencies of over 100 MHz, another type of inductor becomes practical. This is type formed by a length of transmission line. A transmission line is generally used to get energy from one place to another. In the radio communications, transmission lines get energy from a transmitter to an antenna and from an antenna to a receiver.

Types of transmission line

Transmission lines usually take either of two forms, the parallel-wire type or the coaxial type.

A parallel-wire transmission line consists of two wires running alongside each other with a constant spacing. The spacing is maintained by polyethylene rods molded at regular intervals to the wires, or by the solid web of polyethylene. This type of line is used in the television receiving antennas. The substance which is separating the wires is known as dielectric of the transmission line. A coaxial transmission line has a wire conductor surrounded by a tubular braid or pipe. The wire is kept at the center of this tubular shield by means of polythylene beads, or often, by solid or foamed polyethylene dielectric, all along the length of line.