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Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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Frequency sweep

Posted Apr 15, 2016, 7:06 a.m. EDT Studies & Solvers Version 4.4 4 Replies

Shailesh Joshi
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"Hello there

I use HFSS most of the times for frequency sweep and plotting S11 over a range of frequencies to monitor the performance of the antenna and it seems pretty straight forward.

Now in COMSOL I have been trying to frequency sweep it through Frequency-Stationary Study and it takes ages to solve the problem and returns with the following error:

Failed to find a solution.
Divergence of the linear iterations.
There was an error message from the linear solver.
Very ill-conditioned preconditioner.
The relative residual is more than 1000 times larger than the relative tolerance.
Returned solution is not converged.

Considering how simple this operation is, I am missing out on something. Is there any better way to find and plot the S11 against Frequency range?

Can somebody please suggest an alternative or the best way to achieve this?

Cheers
4 Replies Last Post Jun 23, 2016, 7:00 a.m. EDT
Sohan Birla
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Posted: 9 years ago Apr 26, 2016, 5:48 p.m. EDT
I guess the error is stemming from the poor mesh resolution . You need at least 5 mesh elements per wavelength. Enable the physics controlled mesh and select maximum frequency.

Cheer,
I guess the error is stemming from the poor mesh resolution . You need at least 5 mesh elements per wavelength. Enable the physics controlled mesh and select maximum frequency. Cheer,
Shailesh Joshi
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Posted: 9 years ago May 17, 2016, 6:53 a.m. EDT
Hello @Sohan Birla, thanks for the reply. I had tried your suggestions earlier on, but had no success. Is there a tutorial anywhere which shows the frequency sweep in COMSOL?

Thanks
Hello @Sohan Birla, thanks for the reply. I had tried your suggestions earlier on, but had no success. Is there a tutorial anywhere which shows the frequency sweep in COMSOL? Thanks
Sohan Birla
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Posted: 9 years ago May 17, 2016, 11:25 a.m. EDT
In frequency domain solver, frequency field type this range(2.4[GHz], 50[MHz], 2.6[GHz])
This will solve the EM over frequency from 2.4 yo 2.6 GHz at interval of 50 MHz. If your range of frequency are from MHz to THz than meshing need to be done for largest frequency.
In frequency domain solver, frequency field type this range(2.4[GHz], 50[MHz], 2.6[GHz]) This will solve the EM over frequency from 2.4 yo 2.6 GHz at interval of 50 MHz. If your range of frequency are from MHz to THz than meshing need to be done for largest frequency.
Shailesh Joshi
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Posted: 8 years ago Jun 23, 2016, 7:00 a.m. EDT
The problem is solved. Thanks Sohan
The problem is solved. Thanks Sohan

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