Selecting a port excitation also determines which S-parameter will be calculated. If All ports is selected, the simulation is repeated such that each defined port will be stimulated once. With this setting, all N*N elements of the S-parameter matrix of your device will be calculated. In contrast to this, if one specific port is chosen to be stimulated, only N S-parameters of an N-port device are calculated. An exception of this rule is a loss-free two-port device, where all its S-parameters are computed in only one simulation run. In this situation, the fact that the matrix is symmetric for all loss free structures is taken advantage of. The corresponding modes can be selected below.
Finally, it is possible to define a specific selection of port modes by opening the Port mode list... dialog. Here, each port mode is listed separately and can be marked for calculation. The simulation runs are then performed one after another. However, it is also possible to choose a simultaneous excitation of the selected port modes with different excitation signals.