ABSTRACT
Lumped circuit models, such as resistors, capacitors, and inductors, are used to evaluate the response of a circuit relative to low frequency. At sufficiently high frequencies, the lumped model of an element is no longer an accurate representation of its behavior. The distinction between lumped and distributed elements can be best understood by studying the traveling wave in a transmission line. The transmission line can be modeled as an infinite number of cascaded sections of infinitesimal length dx. The importance of the Voltage Standing Wave Ratio (VSWR) comes from the ease of measurement since it is a voltage ratio. The load impedance can be indirectly calculated by measuring the maximum and minimum voltage magnitudes along the transmission line and the location of the voltage minimum. The Smith chart is a graphical tool to calculate the impedance as a function of the reflection coefficient.
