This QUCS hands on lab illustrates how to simulate a 2-port VNA and bring in measured S-parameters to view them various formats.
In the first lab, we set up a simple 2-port VNA and simulate the S-parameters of an ideal, lossless transmission line. The impedance and time delay of the transmission line can be changed to observe the impact on the return and insertion loss.
In the second lab, a uniform lossy transmission line defined by the cross section information of a microstrip is simulated. Note the impact on the insertoin loss. You can adjust the port impedance to reduce the return loss and extract a rough idea of the characteristic impedance of the line.
In the final circuit, the touchstone file from a measured structure is brought into the simulator and the insertion and return loss displayed. There are five different touchstone files provided in this circuit. Double click the file icon and you can view each of these files.