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Does Somebody have experience in PML for Electromagnetic?

Posted Aug 19, 2014, 11:49 a.m. EDT RF & Microwave Engineering Version 4.4 2 Replies

Mohammad Parvinnezhad Hokmabadi
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Hi,

Please let me know if you guys already worked with PML in RF module.
I am doing a very simple structure but I can not implement PML for a long time.

Thanks,
Mohammad
2 Replies Last Post Aug 19, 2014, 3:51 p.m. EDT
Pu Zhang
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Posted: 10 years ago Aug 19, 2014, 3:26 p.m. EDT
You should state more details of your problem. PML in RF module is a quite standard method. Many people might be able to help you if you provide more information.
You should state more details of your problem. PML in RF module is a quite standard method. Many people might be able to help you if you provide more information.
Mohammad Parvinnezhad Hokmabadi
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Posted: 10 years ago Aug 19, 2014, 3:51 p.m. EDT
Thanks Pu,
Actually I am going to re-simulate something like 'scattere on substrate' example of Comsol.
It has two studies, one with periodic and port boundaries which I am kind of familiar.
The second study of that is with PML boundary surrounded the whole structure.
I am not familiar with PML at all.
That is why I am going to simulate a simple 2D structure composed of air and Si. Both materials are semi-infinite.
The whole structure is surrounded by using PML.
I am using 'scattered field' as solve for setting (not Full field).
The direction of propagating is y. The polarization is in either x or z direction
What I am looking for is the reflection off the interface while I am sweeping frequency as range (4.8e14,4e12,8.8e14) Hz.
I implemented PML similar to the second study of 'scatterer on substrate' but I still have problem.
Eventually, after too many error-try I could get good result for x polarization (reflection = 0.3). Then I changed the polarization to z and now it does not give me right reflection (reflection is now almost 0.2).
I also used the same mesh and PML settings (scaling factor=1) to do same simulation in 3D, but the reflection is not even and it is about 0.2 again.
Another interesting thing is this: when I change the dimension of whole structure in 2D case, like make it bigger or smaller, the results are completely wrong.
I am not sure if the scaling factor is not right as it is always 1 in my simulations, although I tried different mesh sizes and scaling factors.
For reflected power calculation, I integrate power flow over a surface in incident side and subtract it from incident power. Then I divide reflected power over incident power.
I am wondering if you can help me.
I attached also the structure in case you would like to take a look that.

Thanks Pu, Actually I am going to re-simulate something like 'scattere on substrate' example of Comsol. It has two studies, one with periodic and port boundaries which I am kind of familiar. The second study of that is with PML boundary surrounded the whole structure. I am not familiar with PML at all. That is why I am going to simulate a simple 2D structure composed of air and Si. Both materials are semi-infinite. The whole structure is surrounded by using PML. I am using 'scattered field' as solve for setting (not Full field). The direction of propagating is y. The polarization is in either x or z direction What I am looking for is the reflection off the interface while I am sweeping frequency as range (4.8e14,4e12,8.8e14) Hz. I implemented PML similar to the second study of 'scatterer on substrate' but I still have problem. Eventually, after too many error-try I could get good result for x polarization (reflection = 0.3). Then I changed the polarization to z and now it does not give me right reflection (reflection is now almost 0.2). I also used the same mesh and PML settings (scaling factor=1) to do same simulation in 3D, but the reflection is not even and it is about 0.2 again. Another interesting thing is this: when I change the dimension of whole structure in 2D case, like make it bigger or smaller, the results are completely wrong. I am not sure if the scaling factor is not right as it is always 1 in my simulations, although I tried different mesh sizes and scaling factors. For reflected power calculation, I integrate power flow over a surface in incident side and subtract it from incident power. Then I divide reflected power over incident power. I am wondering if you can help me. I attached also the structure in case you would like to take a look that.

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