[Enki]

Hi,

I am an Ph.D. and RF engineer who is trying to move to open/free software for design and simulation. I find QucsStudio very interesting and I see it has potential. I would like to participate in teaching and problem solving to improve the software.

Please, contact me if you are interested.

[Enki]

Hi Carsten,

There is an indirect way to do it with Matlab or octave. You can generate a netlist from your schematic with Simulation\Show Last Netlist or shift+F5, and save the file as a txt document.

Then flowchart would be something like this:

1. Load the file in Matlab or Octave
2. Run the simulation with a for loop to go through the lookup table
3. Modify the lines where the capacitor and resistor are to introduce the values you want in each step of the loop
4. Read the ‘dat’ files with the S parameters from simulation
5. Process data in a convenient way for you

I’ve done it in the past for other circuits and it works well. Find attached the matlab functions that will help you to run QucsStudio and read the S-parameters. I built them from the information I gathered time ago in this forum so I am not the original author, I just put the information together for my needs.

Remember to share the solution when you implement it 😀

 

• This reply was modified 4 months ago by Enki.

Attachments:

1. QucsStudio_matlab.zip

[Enki]

Hi,

Try ‘lossy_inductor.sch’ from the Simulation_AC example project.  I ran it myself and it works but I can not make it run in your schematic.

I hope it helps

 

[Enki]

Hi Carsten,

Is this what you want to achieve?

• This reply was modified 4 months ago by Enki.

[Enki]

Hi Carsten,

I wanted to try the QucsStudio EM capabilites with a simple design: end-coupled half-wavelength bandpass filter. One of the task I want to perform for the filter design is to model the gaps between the resonators to calculate their length and link it to the lowpass prototype.

How? 

I created a simple pcb layout with two copper strips and a gap separating both of them. After that, I need to change the gap width, take the s-parameters from the simulation, extract the capacitor pi-model and create a table that relates the lowpass admittance inverters with the EM simulation.

I also need to do a de-embbeding for a more accurate modelling.

By been able to manipulate the layout and run the EM simulation I could automate the process with a matlab/octave script.

What did I get?

I got it with the .sch and TL components but I want a more accurate simulations with the EM option.

What I can’t do?

• De-embedding
• Run the netlist file from a pcb layout using a Matlab/octave script

I’ve included the project with the schematic and layout. You can generate the netlist from both and see they have different formats. When I try to launch a simulation with qucssim.exe it does not work. I believe I could do it by calling qucsfdtd.exe but I don’t know how. I guess that the right person to answer that is Michael Margraf.

Attachments:

1. Gap-modelling-1.qucs

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