What may be possible cause of simulation failure in HFSS?
I have provided air box for radiation also (not shown in image).
But when i simulate (analyze) my design in HFSS then it just kept on simulating ( i have tried for large step size also 4-6 GHz with 0.1 step size) it never stops or converges, I have design for 5.2 GHz so it must converge around it in range of 4-6 GHz.
No error message shown, nothing just it never ends simulating.
Kindly help , is there any infinite loop in HFSS?
What may be possible problems of this case?
From simulation point of view you can try following tricks may be you have tried few or all of them
1. If you know your design frequency just simulate round the design frequency
2. Relax the mesh conditions as goal at hand is not accurate simulation but to identify problem in simulation
3. Monitor your CPU and RAM usage during the simulation though I think HFSS terminates the simulation when RAM usage touches to 90% but better to be sure. If you find RAM engaged with negligible CPU usage it means system is doing nothing
This could be a way out if you are all sure about your design
it runs when i decrease number of passes in setup to 5 from 20.
decreasing no. of passes yield inaccuracy in results, is it so?
Well it means you have one end of riddle.
First about your question about relationship of number of passes and accuracy answer is yeas but about the convergence you always get a message if solution is not converged about the defined number of passes and also you can see in result window what changes in results are produced by each pass. Another very important point is that if you are getting some solution then you can yourself see how accurate it is or not means if you can live with this solution as for me number of passes 20 is too large. As after each pass software check the accuracy criterion defined by user and then refine the mesh again by the percentage change defined by user and then simulate the whole setup again so it means what is actually going on with you since number of passes are 20 so when you run simulation it runs with some optimal settings and since your convergence criterion is so high it keeps on refining the mesh finally reaching to some resource limit and hangs so you see your simulation running for long actually doing nothing. You can confirm this situation by keep the resource window of your PC open so that you can keep any eye on RAM and CPU usage during the simulation and see what happens after each pass. The best solution out of this issue is first try to be sure what you mean by accuracy and how accurate solution you want and if it can be relaxed. On the other hand reduce the number pf passes rather increase the mesh refinement criterion also try to see what is the change in result after every pass