2 - Transmission lines

Abstract

This chapter presents basic principles of transmission lines, discusses Smith charts and s-parameters. It introduces frequently used types of transmission lines. Knowledge of transmission lines is necessary in order to understand how high frequency engineering signals can be efficiently moved from one location to another. Transmission systems are used to transfer energy from one point to another. The energy transferred may be sound power or electrical power, or digital/analogue/optical signals or any combination of the above. There are many types of transmission lines, such as waveguides, coplanar waveguides, and coaxial lines. These ranges from the two wire lines which one can find in their home for table lamps, and three wire lines used for electric kettle. Although these cables work efficiently at power frequencies (50-60 Hz), they become very inefficient at high frequencies because their inherent construction blocks high frequency signals and encourages radiation of energy.