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solving two different frequiencies at the same time

Posted 21 juin 2011, 09:40 UTC−4 RF & Microwave Engineering Version 4.2 3 Replies

Daniel Prestin
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Hi,

I want to simulate a case where I have two different frequencies at the same time and I am interested in the electric field of both. Maybe I not smart enough, but all I reached is to solve the study for each frequencies alone and get two indepentend solutions. How can I connect the variables of both electromagnetic waves to get one solution?
By the way, I am running Comsol 4.2 under Windows 7.
I would be thankful for any answer.

Kind regards

Daniel
3 Replies Last Post 22 juin 2011, 05:58 UTC−4
Edgar Kaiser
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Posted: 1 decade ago 21 juin 2011, 09:57 UTC−4
Hi,

if your system is linear you could try to add the independent solutions for both frequencies. I am not sure if this is possible inside COMSOL or you must export your data.
If the system is nonlinear, you will need to run a transient study and define your input as an explicit function of time like
A1*sin(w1*t) + A2*sin(w2*t).

Cheers
Edgar

Hi, if your system is linear you could try to add the independent solutions for both frequencies. I am not sure if this is possible inside COMSOL or you must export your data. If the system is nonlinear, you will need to run a transient study and define your input as an explicit function of time like A1*sin(w1*t) + A2*sin(w2*t). Cheers Edgar
Daniel Prestin
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Posted: 1 decade ago 22 juin 2011, 05:16 UTC−4
Hi Edgar,

thank you for your quick answer.
For the case of a linear system I could live with the workaround and exported the data to Octave.
But isn't it a shame to not get this to work in Comsol?
And for the case of a nonlinear system I don't know where to input the explicit function you mentioned?

Kind regards

Daniel
Hi Edgar, thank you for your quick answer. For the case of a linear system I could live with the workaround and exported the data to Octave. But isn't it a shame to not get this to work in Comsol? And for the case of a nonlinear system I don't know where to input the explicit function you mentioned? Kind regards Daniel
Edgar Kaiser
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Posted: 1 decade ago 22 juin 2011, 05:58 UTC−4
Daniel,

well, COMSOL can do a lot, but not everything a specific user would find useful is implemented. And in most cases you run a frequency domain study to separate the frequencies. I suggest you issue an inquiry to COMSOL support and they may consider to implement your specific need into a future version.

Regarding the transient study. You must make the way you stimulate the model time-dependent. So, if you use a voltage driven lumped port, you would make that driving voltage time-dependent the way you need.

Cheers
Edgar
Daniel, well, COMSOL can do a lot, but not everything a specific user would find useful is implemented. And in most cases you run a frequency domain study to separate the frequencies. I suggest you issue an inquiry to COMSOL support and they may consider to implement your specific need into a future version. Regarding the transient study. You must make the way you stimulate the model time-dependent. So, if you use a voltage driven lumped port, you would make that driving voltage time-dependent the way you need. Cheers Edgar

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