Springer Science+Business Media Singapore 2016. All rights reserved. This chapter presents the theory of transmission lines, which are essential for the design of radiofrequency (RF) circuits associated with antennas and transmissionline- 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 printedcircuit 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.
