Problem with working on PIFA design in CST

Hi everyone,
I am currently working on PIFA deisng in CST. I have tried many deisng from KIN-WONG book and followed many papers for CST design. Recently i design BRANCH LINE PIFA. Although am getting resonant frequencies 1 GHz and 1.8 GHz but the error am getting with it is"Steady state criterian hasnt been met, maximum number of pulse widths simulated Solver stopped".
Can anybody tell me why is that?
Also has anybody really worked on PIFA design on CST and got the simulations correctly .
If yes could you please give the dimensions and other things?
Thank you

Use a lower value for energy criteria for simulation conclusion. Sounds like you have energy that is still trapped in your model that has not yet dissipated or radiated. Are you sure you are using absorbing boundaries? It might be that your simulation workspace is closed becuase of incorrect boundary conditions and the energy is getting trapped inside the workspace.
--Max

yeah that cud be the reason...I am using open boundary conditions. This pifa design is for GSM 900/1800 MHz. Although i am getting the resonant frequencies at 900 and 1800 MHz but with little bandwidth. I am using CST , so in boundary conditions it gives options either with open add space or open. Do you any idea wt could be the Mesh cells size? I will try different boundary conditions.

It would be better if you upload your file.

I think it's better to use "Open--Add Space". That way, it's less likely that you might have absorbing boundaries too close to your model, where they might absorb the field lines in a non-physical manner.
If you have 2-3 cells through the thickness of your dielectric, you should be OK. You might want to place a mesh control definition on the dielectric body to enforce this.
--Max

Hi,
Try to increase the number of simulated pulse widths. You will find it in the Transient Solver dialog box under "Specials".
P.