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 The information provided may be out of date.

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

Oblique incidence and floquet condition problem

Please login with a confirmed email address before reporting spam

In the RF module, I found that there are 2 problems.

First,
When the thickness of the layer which uses scattering boundary condition gets thin (below ~200nm), the direction of power flow [sqrt(emw.Poavx^2+emw.Poavy^2+emw.Poavz^2)] doesn't go 90 degrees even if I set the incident angle as 90 degrees.

Second,
The power flow distribution reaches below some part of port condition area even if I set the incident angle as 90 degrees.

I also tested it in the plasmonic wire grating of model library which uses port condition instead of scattering boundary condition. However same problems occurred.

I attached figures of my question.

please help me.


2 Replies Last Post 16 gen 2013, 12:59 GMT-5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 16 gen 2013, 00:57 GMT-5
Hi

but if you go too thin, the skin effect will make the material more and more "transparent", and the amount of energy passing will influence the E field hence act on the angle, no ?
But I might have missed something

--
Good luck
Ivar
Hi but if you go too thin, the skin effect will make the material more and more "transparent", and the amount of energy passing will influence the E field hence act on the angle, no ? But I might have missed something -- Good luck Ivar

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago 16 gen 2013, 12:59 GMT-5
First of all, you should use 1 set of periodic BC, not 3 identical. Helps avoiding mistakes :)
Second, use ports instead of scattering BC.
Third, floquets are implemented correctly in COMSOL. I've tested the results vs. independent EM solvers.
Finally, regarding oblique angles: your model is not setup correctly to launch waves at 90 degrees. So what you are seeing is some kind of artifact.
First of all, you should use 1 set of periodic BC, not 3 identical. Helps avoiding mistakes :) Second, use ports instead of scattering BC. Third, floquets are implemented correctly in COMSOL. I've tested the results vs. independent EM solvers. Finally, regarding oblique angles: your model is not setup correctly to launch waves at 90 degrees. So what you are seeing is some kind of artifact.

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.