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PML and periodic boundary on the same 3D RF

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Hello,

I will be very happy if someone can help me with the use of PML and periodic conditions on the same 3D RF model with COMSOL 4a. It is simple to implement periodic boundary conditions following the "periodic boundary condition model". However, once i include the PML, i cannot excite a plane wave using scattering boundary conditions. I have to place the Scattering boundaries on the outer boundaries of the PML, which doesn't have the same effect as exciting the wave directly in the medium. Is there any other way of exciting a plane wave with an angle right below the PML in the medium? Thanks in advance!

-Filiz

3 Replies Last Post 29 août 2010, 07:26 UTC−4

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Posted: 1 decade ago 18 août 2010, 05:29 UTC−4
In 3.5a it was possible by selecting an interior boundary, enable the option of use interior boundaries, and then specifying the magnetic field. But the was not usually the best solution since this boundary is fixed up to the specified value meaning that any backscattered wave will be repelled away. Scattering boundaries, on the other hand, are 'soft' boundaries in that they let the backscattered waves reach them as if they are moving in free space medium.

What you could do is to choose scattering analysis and then define incident plane wave in the field of incident field specification. That would automatically excite the specified field in the geometry without having you to do it via scattering boundary. This allows you to wrap around your entire geometry with PMLs as well.

If there is one, I suggest you to check any standard scattering computation model in the model library. That should hopefully illustrate the idea, as it did in 3.5a
In 3.5a it was possible by selecting an interior boundary, enable the option of use interior boundaries, and then specifying the magnetic field. But the was not usually the best solution since this boundary is fixed up to the specified value meaning that any backscattered wave will be repelled away. Scattering boundaries, on the other hand, are 'soft' boundaries in that they let the backscattered waves reach them as if they are moving in free space medium. What you could do is to choose scattering analysis and then define incident plane wave in the field of incident field specification. That would automatically excite the specified field in the geometry without having you to do it via scattering boundary. This allows you to wrap around your entire geometry with PMLs as well. If there is one, I suggest you to check any standard scattering computation model in the model library. That should hopefully illustrate the idea, as it did in 3.5a

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Posted: 1 decade ago 18 août 2010, 14:36 UTC−4
Thanks so much Shakeeb! It was very helpful. I checked "radar cross section model" for scattering computation model and implemented that with periodic conditions it worked very well!

Filiz
Thanks so much Shakeeb! It was very helpful. I checked "radar cross section model" for scattering computation model and implemented that with periodic conditions it worked very well! Filiz

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Posted: 1 decade ago 29 août 2010, 07:26 UTC−4
Hi Filiz,

I'm very interested in generating the same type of wave you did. Could you please upload your model? I would really appreciate it!

Thanks in advance!
Hi Filiz, I'm very interested in generating the same type of wave you did. Could you please upload your model? I would really appreciate it! Thanks in advance!

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