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How to use symmetry plane in HFSS?

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zarzar4000

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hi friends
i face a problem!!!
my project takes lots of time to be solved.
i want to reduce the time, i want to use symmetry plane in hfss but i am familier enough how to do that.
does using symmetry plane change the final solution?
i attach my project ,
guide me please!
 

roxxon

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Re: hfss symetry plane

In my experience, yes, a symmetry plane does change the result -- although it is not supposed to, when applied correctly. I think it is a tradeoff, shorter simulation time vs. accuracy.

I tried it with your model and there was a slight alteration -- but maybe that can even be avoided when some time is spent on meshing options etc. I applied a perfect H symmetry (make shure you apply the impedance multiplier accordingly, for one H symmetry set it to 0.5) in the xz plane.

However, in cases like yours I suggest to seed the meshing by doing the following: copy your star (the antenna), sweep it along the z-axis by about lambda/20 or something like that and apply vacuum. Normally you do not even have to apply any meshing operations (although sometimes that further enhances the situation) but the meshing is better and faster convergence is obtained. Therefore fewer adaptive meshing steps have to be done, a more coarse meshing can be used and you save a lot of solving time.

Hope that helps in your case as well.
 

zarzar4000

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Re: hfss symetry plane

thanks roxxon

you know,my real project is to optimize that antenna,so i have to put it in the loop of optimization and it is very time consuming.
i have no way to accept that much alteration due to using symmetry plane.
but i did not understand what u say about sweeping my antenna:?:
what is the usage of that sweeping?do u mean changing the radiation box?

another problem that i have,(may be u can help me!!):
i want to have a dual band antenna in 2.4 and 5.8 GHz,
i made a setup in hfss with f0=5.8GHz and two disceret sweep for 2.4 and 5.8.
is my work true or not?

thanks!!!
 

roxxon

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Re: hfss symetry plane

As for the sweeping: mark your antenna patch (perf E sheet), copy and paste it again and then right-click for the pop-up menu, choose Edit -> Sweep -> Along Vector. Click anywhere (two clicks), so that the command is finished. Then go look up the new solid body, probably under vacuum or not assigned and double click on the SweepAlongVector. In the vector, set e.g. 0,0,lambda/20 and set 0.3/2.4 for lambda. Maybe you need to play somewhat with the factor... lambda/10 or lambda/50 or something like that usually gives me much faster convergence - without applying any mesh operations on this new solid body. Just make sure, that to delete the Perfect E-boundary, which is also copied during the process.

As for the frequencies: i would not use a discrete sweep in this case, where the frequencies are that far from each other. I would set up two separate setups, one for 2.4 and one for 5.8 GHz.

By looking at the model you uploaded I found that you did not apply a radiation boundary at all. Obviously you have to apply radiation boundary to your outside vacuum container, which you called "radiation" by Assign Boundary -> Radiation.
Also, the lumped port is just the width and height of the microstrip line, not as large as yours; yours kind of looks like a waveport ;-)
 

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