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dispersion relations/frequency dependence

Posted 22 sept. 2009, 23:37 UTC−4 Studies & Solvers 1 Reply

Mike H
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Hey everybody,

I am trying to use comsol to model an RF system where an antenna is being driven at multiple very different (order of magnitude) frequencies, and I want the materials to have a realistic dispersion relation. What's the best way to do this? I've been working in the transient domain (actually the easiest way to do this problem, but I can move to frequency space with an FFT of my driving signal) and it really seems like there isn't a way to specify the impulse response or whatever, and if done with a harmonic analysis I don't know how to specify the set of frequencies in my signal.

If I wanted to, is there a way to solve the same model at different frequencies and superimpose the results? If everything is linear then this would work, but it's very far from ideal.

and, to commit a heresy: if COMSOL can't do this, does anybody know a package that can?

thanks!
Mike
1 Reply Last Post 18 déc. 2009, 19:10 UTC−5
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Hello Mike H

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TIAN ZHOU
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Posted: 1 decade ago 18 déc. 2009, 19:10 UTC−5

Hey everybody,

I am trying to use comsol to model an RF system where an antenna is being driven at multiple very different (order of magnitude) frequencies, and I want the materials to have a realistic dispersion relation. What's the best way to do this? I've been working in the transient domain (actually the easiest way to do this problem, but I can move to frequency space with an FFT of my driving signal) and it really seems like there isn't a way to specify the impulse response or whatever, and if done with a harmonic analysis I don't know how to specify the set of frequencies in my signal.

If I wanted to, is there a way to solve the same model at different frequencies and superimpose the results? If everything is linear then this would work, but it's very far from ideal.

and, to commit a heresy: if COMSOL can't do this, does anybody know a package that can?

thanks!
Mike


hei, Mike

did you figure out the problem?
for frequencies, goto physics--scalar variables--nu_rfwe.
i am not sure how to set a dispersion of material properties (i guess here you mean dielectric properties), coz i am a newbie too.
for simulation, Ansoft and CST have some, but i am not sure if they can do a better job than Comsol in your application
[QUOTE] Hey everybody, I am trying to use comsol to model an RF system where an antenna is being driven at multiple very different (order of magnitude) frequencies, and I want the materials to have a realistic dispersion relation. What's the best way to do this? I've been working in the transient domain (actually the easiest way to do this problem, but I can move to frequency space with an FFT of my driving signal) and it really seems like there isn't a way to specify the impulse response or whatever, and if done with a harmonic analysis I don't know how to specify the set of frequencies in my signal. If I wanted to, is there a way to solve the same model at different frequencies and superimpose the results? If everything is linear then this would work, but it's very far from ideal. and, to commit a heresy: if COMSOL can't do this, does anybody know a package that can? thanks! Mike [/QUOTE] hei, Mike did you figure out the problem? for frequencies, goto physics--scalar variables--nu_rfwe. i am not sure how to set a dispersion of material properties (i guess here you mean dielectric properties), coz i am a newbie too. for simulation, Ansoft and CST have some, but i am not sure if they can do a better job than Comsol in your application

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