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Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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Scattered field with a mirror

Posted 26.09.2012, 10:47 GMT-4 RF & Microwave Engineering, Mesh, Modeling Tools & Definitions, Parameters, Variables, & Functions, Studies & Solvers Version 4.3 4 Replies

Matth Duperron
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Hello,

I have a problem with boundary conditions. I'd like to study the scaterring field of a metallic object on a mirror (in 2D).
I create a box with PML on each side. I use the "solve for: scattered field" setting with a field Ex=E0*exp(j*emw.k0*y) and I verify that if i work in air, the side PMLs don't interfere with my plane wave. But when i add a mirror, the PMLs disturb my electric field and seems to create periodic interferences perpendicular to the mirror surface.
I tried different other boundary condition to avoid this problem but i haven't yet find the solution.
Did anyone already have this problem?
thanks

Mat
4 Replies Last Post 27.09.2012, 08:13 GMT-4
Alexander Kuznetsov
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Posted: 1 decade ago 26.09.2012, 16:46 GMT-4
Make PML thicker, move it further and mesh it finer.
Make PML thicker, move it further and mesh it finer.
Matth Duperron
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Posted: 1 decade ago 27.09.2012, 04:25 GMT-4
That's seem to make no difference.
Actually, i have also the problem without mirror, just a plane wave with PML. I attach the mph file to this message.
I'm surely doing something basic wrong, but what?
That's seem to make no difference. Actually, i have also the problem without mirror, just a plane wave with PML. I attach the mph file to this message. I'm surely doing something basic wrong, but what?

Attachments:

Andrea Ferrario COMSOL Employee

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Posted: 1 decade ago 27.09.2012, 05:15 GMT-4
Hi Mat,

The top and bottom layers extend all the way to the sides. You need to add separate domains at the "corners" of your PMLs. See page 239 of the User's Guide for an example image.

--
Andrea Ferrario
Electromagnetics Group
COMSOL AB
Hi Mat, The top and bottom layers extend all the way to the sides. You need to add separate domains at the "corners" of your PMLs. See page 239 of the User's Guide for an example image. -- Andrea Ferrario Electromagnetics Group COMSOL AB
Matth Duperron
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Posted: 1 decade ago 27.09.2012, 08:13 GMT-4
Indeed, that's much better!
But now, when i add my gold mirror, i have important interferences who do not disappear with the length of my box or the mesh size.
An idea?
Indeed, that's much better! But now, when i add my gold mirror, i have important interferences who do not disappear with the length of my box or the mesh size. An idea?

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