High‐Frequency Transmission Lines

Abstract Transmission lines are used to guide electromagnetic waves from one place to another. They are used for many types of applications; the most common application in high frequencies is the transmission of signals, either digital or analog. In this case, high‐frequency transmission lines are often designed to maximize the operable frequency bandwidth and minimize the attenuation of the signals. The former preserves the quality of the signal being transmitted, while the latter increases the maximum possible distance of transmission. Examples of high‐frequency transmission lines include coaxial cables, optical fibers, microstrip lines, and hollow waveguides. Transmission of signals is not always limited to physically long lines. Some high‐frequency transmission lines are also used for short‐distance transmission as, for example, those used to transmit signals within a computer or to feed an antenna from its source. This chapter discusses various types of high‐frequency transmission lines used in RF and microwave applications and the various propagation mechanisms behind their operation.