CPW resonator using CST

[JJMao]

Hello,

I am currently trying to simulate a CPW resonator @ ~7GHz using CST microwave studio. I've attached the cst file in case people want to help.
At the moment I'm not getting any good results, the S21,S11 parameters are flat, no peaks or dips.
Not sure what I have done wrong in my design, the ports I defined are larger than the ones you would normally make for a cpw structure because the S21, S12 parameetrs where too low (-70 ~ -90 dB).

Could anyone please help with a suggestion?

Thank you

 

[sme9572]

Hi , first of all , u must change your units to nm , then your waveguide ports have improper range , u should change it , and after that u can run it , but after some seconds , u will get error and solver had to stop , i attached a picture of problem , that u can see , the problem is about background material, try to find the problem , i haven't any idea about that.

https://upload7.ir/images/96049417498932075173.png

 

[JJMao]

Thanks for your reply

I am not sure I understand why my ports have improper range, the settings are in um and ports are um size. I will change to nm and see what happens.

I never had that background material error, I assumed the software takes the surroundings to be air by default. What cst version are you using?

Lastly, can I ask what simulation you ran: Time domain/ Freq dom/(...), what frequency range, etc. I am interested if you have made any other changes to the settings in the file I uploaded so I know what to improve, like meshing for instance, not sure if meshing is done properly.

Thank you

 

[sme9572]

i'm using CST 2013 , check pic , solver is run it.

download file


https://upload7.ir/images/33159581184713197418.png

 

[JJMao]

I downloaded the file but couldn't see any results.
Can you give me a screenshot of your S-parameters results, I just want to get a dip/peak at aroung & 7.3 GHz, and a homogenous magnetic field around the meandered section of the resonator.
The problem I had was that S21 was very low (-90db) which suggested I wasn't getting anything at the output.

----

Apologies, just realised I'm an idiot and made the metalic film from alumina (Al2O3) and not aluminun. Changed it (see uploaded file), but still can't get any good results.

 

[sme9572]

problem are at waveguideports and maybe at boundary condition , try to change them to different , check pic

https://upload7.ir/images/49270371631002464155.png

 

[JJMao]

I have solved the wvguide port and boundary conditions problem. However I don't get any dips in S21, S11, which would indicate my circuit is resonant.
I don't understand what the problem might be.

I uploaded the updated cst model and results

 

[JJMao]

Here are the attachments