Sparameterien

Sparameterien, also known as scattering parameters or S-matrix, are a set of values that describe the electrical behavior of linear electrical networks, especially at high frequencies. They are particularly useful for analyzing microwave circuits and components like amplifiers, filters, and antennas. Instead of dealing with currents and voltages directly, which can be difficult to measure and control at high frequencies due to reflections and transmission lines, S-parameters relate the incident and reflected power waves at the ports of a network.

Each S-parameter, denoted as S_ij, represents the ratio of the outgoing power wave from port j to the incoming power wave at port i, assuming all other ports are terminated with a characteristic impedance, usually 50 ohms. For a two-port network, there are four S-parameters: S11, S12, S21, and S22. S11 describes the reflection at port 1, S21 describes the transmission from port 1 to port 2, S12 describes the transmission from port 2 to port 1, and S22 describes the reflection at port 2. These parameters are complex numbers, meaning they have both magnitude and phase information, which is crucial for understanding how a device affects signals in terms of gain/loss and phase shift. They are typically presented in a matrix form, hence the term S-matrix.