transient setting of "accuracy" for cst

[yikie]

hi everyone...
For the transient setting of the "accuracy" part, is it must be set below -30 dB?if i set it -20dB,how i can know that whether my s parameter is correct or acceptable or not?

thank you.

 

[Element7k]

You can look at the energy balance for a passive device. Also, if you vary the accuracy and you get different results then you probably need to set it to a higher value.

 

[yikie]

May I know where i can look for that energy balance?and is it you mean that for the correct accuracy, we will get the the same result even we increase the accuracy value?

 

[Element7k]

Sorry I meant power balance - its in the result tree. For passive structure this is less than 1 and if lossless structures, close to 1. If you change the accuracy setting e.g. from -20 to -60 db and there is no significant change in s11 and field data then you should not need to increase the accuracy. The accuracy setting will stop the simulation when energy within the structure has decreased to a level of your desired setting. E.g. it maybe difficult to reach say -60 dB in a highly resonant strucutre.

 

[yikie]

Power balance?is it the "balance" in the 1D results?and actually what it indicated for.Now i'm designing a tag antenna,but my result is quite different for the -20dB and -30 dB.so mean that -20 dB result is not accurate and i should try increase my accuracy to -40 or -50dB to see whether the result is same or not??

 

[Element7k]

Yes your assumption is correct. -20 dB is insufficent if you result differ between -30 and -20. Yes, I am refereing to the "balance" in 1D result. You can refer to help in CST for a defination of power balance.

 

[yikie]

really thanks you so much for your help....