Transmission Lines

This chapter presents the theory of transmission lines, which are essential for the design of radiofrequency (RF) circuits associated with antennas and transmission-line-based antennas. It includes the transmission-line equations and important transmission-line parameters such as characteristic impedance, propagation constant, phase velocity, effective relative dielectric constant, dispersion, loss, distortion, impedance, reflection coefficient, etc. It also presents synthetic transmission lines, a class of transmission lines that can be implemented using only lumped elements, which could be useful for RF circuits needed for on-chip antenna interface. Moreover, the chapter covers the most commonly used printed-circuit transmission lines for RF systems, which also include those that can be realized in multilayer structures that are attractive for printed-circuit antennas and associated RF circuits.