Has anyone tried simulating a GCPW in CST? I have simulated in ADS and got desired results and now I want to simulate the same line in CST so I can use it with another model in CST. But I am unable to make the S parameter results from ADS and CST to match. I believe it's a problem with port definitions. Has anyone successfully simulated a GCPW in CST? I couldn't find anything that worked on any forum.
It should work - you need to make sure that your port is big enough to hold the required modes, and that your boundary conditions don't short out things that should be open circuit. Can you show us a cross-section of your port with an indication of the wavelength?
try port width 3(2g+w) and height 4h, where g is the gap between conductor and side ground, w is the width of conductor, h is the height of substrate. I read it online for HFSS.
In manual it is given to be 10w x 8h (width x height). hope it helps
Malcolm White I believed it will work but it doesn't. I have attached a screenshot of the port. Hopefully, you can understand it better than me and can tell what's wrong.
Nitin Kumar that was the first thing I tried but didn't work
I think your port is too wide. If it is over half a wavelength wide then there can be a waveguide mode in the substrate, which is what CST will use as the first mode. You need to narrow the port or put in grounding strips to narrow the width of the dielectric so the waveguide mode can't go in. Narrowing the port works.
I ran CST with the geometry you have shown (rough proportions and I don't know your wavelength) and it worked when I made the port narrow enough. Look at the port mode - if it is all below the tracks then it is a waveguide mode. The mode you want has all the fields in the narrow slots in the track. Did you make the port narrow enough? It needs to be less than half a wavelength in the substrate.
I used ptfe as substrate and made the port 6 mm wide and it worked from DC to 20 GHz. Above that it wasn't too bad either, but had some dips in transmission, maybe due to length resonances.
In the mentioned tutorial they have explained clearly. Try this:
https://slideplayer.com/slide/5901733/.
Ninad Chitnis
You need to use the multipin ports inside the waveguide window - see info in the help. The central pin you will attach the (+) polarity. Both lateral grounds will have (-). As for the inferior ground plane you can leave it unassigned or check it as (-) too - see if the impedance/field pattern is the expected to confirm the port setup. By doing so you will tell the engine your expected mode is the odd one, which is supposed to propagate in an ordinary CPW transmission line.
Just bear in mind that when you tell CST that all these patches are connected (by assigning "-" to them) the real-world structure should be made as well - by means of potential equalizing pins/vias. CPWs are tricky nasty structures.
Thanks for the help. Turns out it wasn't the port that was the problem. The boundaries were!
Hi ;
upper and lower boundary condition of the plate = magnetic field
other parties = electric field
Given that you said in your question that you simulated GCPW in ADS:
would you please tell me that How simulat grounded coplanar waveguide in ADS?
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