Home › Forums › Usage › usage stoz function This topic has 4 replies, 2 voices, and was last updated 2 months, 2 weeks ago by Carsten. Viewing 5 posts - 1 through 5 (of 5 total) Author Posts 19. November 2022 at 0:14 #6780 CarstenParticipant Hi, I tried qucsStudio today for the first time and I like it. I want to plot the impedance loading a signal source. I used to do Z_param = stoz(S) in Qucs. QucsStudio gives Error in ‘Eqn4’: Different variable sizes in equation “stoz(S)”. The german QucsStudio Help says: stoz(Z): transformiert S-Parameter mit Referenzimpedanz Z nach Z-Parameter, Parameter Z ist optional, default ist 50, unterschiedliche Impedanzen sind möglich, z.B. [25, 75] So the function does not accept an S matrix as a parameter, but only the impedance? Confusingly, this is listed under “Funktionen nur in Schaltungsformeln”. Does this refer to the Gleichung / Equation object? 19. November 2022 at 0:16 #6781 CarstenParticipant How do I attach a .sch file to my post? I get an error “Sorry, this file type is not permitted for security reasons.” But others here in the forum seemingly managed to do it. 19. November 2022 at 1:05 #6784 CarstenParticipant This old forum post: http://qucsstudio.de/forums/topic/tutorial/ refers to the “formula” item in the diagrams folder. Is stoz() meant to work with that? 20. November 2022 at 20:24 #6786 QucsStudioKeymaster The correct usage of z-parameter transformation is: Z_param = stoz() if your s-parameter ports have 50 ohms Z_param = stoz(25) if your s-parameter ports have 25 ohms This works in equation components only, not in diagram equation. Anyway, if you want to know the loading of the source, stoz() is not the correct function, because z-parameters are defined with open port terminations. rtoz(…) does the job (see attached picture). 20. November 2022 at 21:33 #6790 CarstenParticipant Ah, yes. Thank you! BTW: For a one port device, rtoz and stoz are the same. Author Posts Viewing 5 posts - 1 through 5 (of 5 total) You must be logged in to reply to this topic.