Unstable calculation when simulating resonator in MWS

Hi all,
I am simulating a resonator structure in MWS. For some setups, the calculation is becoming unstable as the output signal starts growing (may be exponentially). What could be the causes of this problem ? All inputs are most welcome. Thank you.
-svarun

Hi Svarun,
this could have several reasons. Could yo post the structure here?
F.

Hello Svarun,
I would start by altering the mesh properties:
1. Try changing lower limit ratio, lines per wavelength etc.
2. See if u can turn off the automesh - and set individual mesh for each part of the model.
3. Try setting a lower frequency sweep (If using a transient solver).
If you have two different versions of CST MWS, try running the model on both and see if its a version bug (who knows...?).
Good luck,
P.

Hi RFSimulator and Pushhead,
The energy reaches -32dB and then starts climbing up. Can I stop the simulation at -30dB and then use AR filter for signal interpolation ? Will this result in accurate results ? Please let me know.
Thanks

Sorry, i'm not acquainted with the AR filter manipulations - I use the default settings.
However, what you describe sounds very similar to couple of simulations I did, at the end the problem was solved by changing the mesh (not necessarily decreasing it).
Can u post the *.mod,*.par file ?
Regards,
P.