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Define an arbitrary EM wave

Posted Aug 7, 2013, 10:19 a.m. EDT RF & Microwave Engineering, Heat Transfer & Phase Change Version 4.3b 4 Replies

John Smith
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Hello
I am new in Comsol and i have a problem :
i want to calculate SAR for SAM phantom for different types of EM waves. but the source of EM waves ( signal generator ) isn't important. is there any wave to just define wave equation ? for example just define an incoming Gaussian wave and see its effects ?
Can i use Comsol model (SAR in human head) and remove the antenna and define an incoming EM wave instead of it ?
4 Replies Last Post Aug 18, 2013, 6:04 a.m. EDT
Robert Koslover Certified Consultant
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Posted: 1 decade ago Aug 12, 2013, 9:56 a.m. EDT
I think you should be able to do this using the RF module in the transient (aka, time-domain) formulation. That way, you can specify a wave as a function of time. And you can even use the built-in gaussian function.

I think you should be able to do this using the RF module in the transient (aka, time-domain) formulation. That way, you can specify a wave as a function of time. And you can even use the built-in gaussian function.
John Smith
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Posted: 1 decade ago Aug 12, 2013, 10:21 p.m. EDT
Dear Robert
Thank you. i see but to specify a spacial direction , we should used Ports ?
Dear Robert Thank you. i see but to specify a spacial direction , we should used Ports ?
Robert Koslover Certified Consultant
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Posted: 1 decade ago Aug 15, 2013, 9:37 p.m. EDT
If you define a geometric face as a "scattering boundary condition," you can specify the individual vector components of the fields and also of the k vector on that boundary, thus giving you general control of the wave direction, field amplitude and phase distribution, etc. Just be careful to do all your trigonometry and complex-fields-defining correctly. The "port" boundary conditions offered in the RF module appear to be of more-limited utility in the time-domain than in the frequency-domain. In the frequency domain, I use ports for most of my RF sources.

Added later: I regret implying that you should or must use complex fields. Using real-valued fields in time-domain mode should work fine.
If you define a geometric face as a "scattering boundary condition," you can specify the individual vector components of the fields and also of the k vector on that boundary, thus giving you general control of the wave direction, field amplitude and phase distribution, etc. Just be careful to do all your trigonometry and complex-fields-defining correctly. The "port" boundary conditions offered in the RF module appear to be of more-limited utility in the time-domain than in the frequency-domain. In the frequency domain, I use ports for most of my RF sources. Added later: I regret implying that you should or must use complex fields. Using real-valued fields in time-domain mode should work fine.
John Smith
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Posted: 1 decade ago Aug 18, 2013, 6:04 a.m. EDT
Thank You
I got it
Thank You I got it

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