ABSTRACT
A transmission line is an electromagnetic guiding system for efficient point-to-point transmission of electric signals (information) and power. Since its earliest use in telegraphy by Samual Morse in the 1830s, transmission lines have been employed in various types of electrical systems covering a wide range of frequencies and applications. Examples of common transmission-line applications include TV cables, antenna feed lines, telephone cables, computer network cables, printed circuit boards, and power lines. A transmission line generally consists of two or more conductors embedded in a system of dielectric
composed of a set of parallel conductors. The coaxial cable (Fig. 6.1a) consists of two concentric cylindrical conductors
separated by a dielectric material, which is either air or an inert gas and spacers, or a foamfiller material such as polyethylene. Owing to their self-shielding property, coaxial cables are widely used throughout the radio frequency (RF) spectrum and in the microwave frequency range. Typical applications of coaxial cables include antenna feed lines, RF signal distribution networks (e.g., cable TV), interconnections between RF electronic equipment, as well as input cables to high-frequency precision measurement equipment such as oscilloscopes, spectrum analyzers, and network analyzers.
