This will download the updated S-parameter plotting program:
I was surprised to discover that the final Touchstone 1.1 file specification provides for multiple, real-valued reference impedances. The plotting program will handle these files.
The maximum reference impedance is 9999 ohms. This seems reasonable given VNA accuracy limitations for high impedances. Some interesting devices are beyond this limit (e.g., 27k ohms for Collins mechanical filters). Shunt capacitance can go to 9999 pF.
The program is not intended to replace NanoVNA-Saver or NanoVNA-App. It provides a convenient way to display all S-parameters, including S12 and S22, and to use the full set for reference impedance renormalization. It handles a different reference impedance for each port, with or without shunt capacitance. No need to build a special, impedance-matching test fixture to measure a filter with nonstandard, unequal impedances. The program provides the stray-cancelling Y21 series-through impedance measurement as well as the usual S21 and S11 series and shunt methods.
Brian
