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steady state energy criterion in CST

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DrunkBear

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steady state energy criterion

"maximum number of pulse widths simulated,Solver stopped.please note that the steady state energy criterion has not been reached"
i suppose this is a very common warning that many have come across, but i didn't get effective solutions when i searched this topic in the forum.
How did you solve this problem? Thank you very much!!
 

RFSimulator

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maximum number of pulses reached

Hi,

this waring is only relevant if you use the time domain solver. Time domain solvers calculate how a pulse propagates thru your structure. In order to get the frequency domain datas an Fourier Transform of the time domain dates is performed. In order to make sure that the Frequency data are correct, the "entire" time pulse has to be calculated. Theoretical, the pulse response of many real structures in infinite long but since the time signal will finally decay exp. with time it is sufficient to take into account "most" of the time pulse. In order to determine how much of the pulse MWS should take into account the program looks at the energy stored in the system and waits till the energy is down to a user given level. In addition, the program also will stop if a certain numbers of excitation pulse length has been reached.

Both number can be influenced by the user. You can specify a energy accuracy level in the main solver menu and the "numbers of pulses" in the special settings of the time domain solver under "steady state" .

F.
 

DrunkBear

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cst steady state

RFSimulator said:
Hi,

this waring is only relevant if you use the time domain solver. Time domain solvers calculate how a pulse propagates thru your structure. In order to get the frequency domain datas an Fourier Transform of the time domain dates is performed. In order to make sure that the Frequency data are correct, the "entire" time pulse has to be calculated. Theoretical, the pulse response of many real structures in infinite long but since the time signal will finally decay exp. with time it is sufficient to take into account "most" of the time pulse. In order to determine how much of the pulse MWS should take into account the program looks at the energy stored in the system and waits till the energy is down to a user given level. In addition, the program also will stop if a certain numbers of excitation pulse length has been reached.

Both number can be influenced by the user. You can specify a energy accuracy level in the main solver menu and the "numbers of pulses" in the special settings of the time domain solver under "steady state" .

F.

Thank you for giving me the instant reply again!
Actually i spent a whole day yesterday studying "help" about some basic principles of CST concerning "T! solver" such as steady state energy, accuracy criterion, maximum numbers of pulses etc. Your reply gave me a review of all this in detail and thank you!
However, according to the rough result the simulation offered, it seems the problem could not be fixed by simply changing those two options.
I tried to modify the"maximum number" to 40-->60(20 defaulted) while specifing the "accuracy" as -30dB, but it didn't get better. In my opinion, the reason of this is that my model(a CRLH based dual-band antenna) is intrincically a resonant structure. The energy could hardly dissipate even if the number of pulse is added, the effect of which is only the prolonged simulation duration! This could be seen from the oscillation of "O1,1" of the "port signals" in the navigation tree.
Could your pls be kind enough to help see my model? In this model, the adaptive mesh refinement is also applied, and you could find the "O1,1", ripple of the S11 curve and bad balance, etc.
Thank you very much!
 

huvarda

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how to create a signal in cst

Most of the time, if I see that kind of warning during the simulation, first I check the units. If units are OK, then check if your design has any features that CST graphic tool doesn't understand. This happens most of the time, if you importing your model from autocad or any other drawing tool. And before any simulation, try to heal all the shapes.
 

DrunkBear

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maximum number of pulse widths simulated

huvarda said:
Most of the time, if I see that kind of warning during the simulation, first I check the units. If units are OK, then check if your design has any features that CST graphic tool doesn't understand. This happens most of the time, if you importing your model from autocad or any other drawing tool. And before any simulation, try to heal all the shapes.

The units are all right.This model was drawn in CST myself and i'm sure all components could be recognized by the system.
Thank you all the same!
 

RFSimulator

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energy criterion cst

Hi DrunkBear,

happy Christmas! the *.par file is missing in your zip archive.. All the used parameters are stored in this file. I therefore can not open your structure. If you use the macro file -> make archive. All the relevant project data are stored in a zip file..

F.
 

DrunkBear

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cst solver start stop

RFSimulator said:
Hi DrunkBear,

happy Christmas! the *.par file is missing in your zip archive.. All the used parameters are stored in this file. I therefore can not open your structure. If you use the macro file -> make archive. All the relevant project data are stored in a zip file..

F.

Hi RFSimulator,
By examine "Advanced Topics" and help files, the problem has almost been fixed.
Actually, it was a typical stronly resonating structure and also a good example of AR-Filter application.
BTW, you mean the mod connot be opened without *.par or it can be opened but no simulation results are ready?
Many thanks for your warmhearted help and it's nice having discussion with you!
 

vioamethyst

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Drunkbear: i experience the same warning, may i know how u fixed it? i tried the suggested solution, increase pulse no, but still it doesnt help any.
(i don think this related to accuracy level)

TQ
 

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