Basics of S-parameters

In this course we will discuss scattering parameters, or S-parameters. This is a method of network characterization that describes what happens to an input wave that impinges on one of the ports. This input signal may be reflected at the port or it may be transmitted through the system to one or more output ports. Typically, this isn’t an all-or-nothing proposition; some of the wave gets reflected and some gets transmitted. S-parameters, therefore, are used to describe how much of the wave follows each of these trajectories. The scattering parameters of an N-port network consists of an NxN matrix, where each matrix element describes a possible trajectory for a voltage wave impinging on a port — either reflecting back out that same port or transmitting through to another port. We will first talk through the definition of the S-parameters, then we will work through an example. This course was created for Ansys Innovation Courses by Dr. Kathryn Leigh Smith, assistant professor, UNC-Charlotte, in partnership with Ansys.