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 The information provided may be out of date.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.

Does Far-Field Calculation with 2-D Fluoquet Boundary Condition make any sense?

Please login with a confirmed email address before reporting spam

Dear Community members,

I was using Background and Scattered Field method simulating an infinite 2-dimensonal array, and the result matches almost perfectly with our experimental results. We wanted to get more physics from the simulation results, thinking about calculating whether there are higher order scatterings and how they behavior in the near-field or far-field. We utilized the far-field domain calculation by including enclosing surfaces of both our non-periodic ports along z-direction and the Flouquet boundary conditions along x and y directions. We have obtained a radar plot from that far field calculation, but we are unsure able the validity of Stratton-Chu formulae for 2-D periodic boundary conditions.

Does the far-field calculation in this case make any sense? From our intuition, waves doesn't comply with the periodic boundary conditions will vanish, which means we can only receive signal from the directions of diffraction orders. However, our far-field calculation show a non-zero broad peaks instead, so it implies some of the far-field calculation assumptions are not fulfilled or it is a consequence of the finite third dimension of a 2-D array, or the absorption of the materials in the unit cell?

1 Reply Last Post Nov 16, 2016, 3:45 p.m. EST
COMSOL Moderator

Hello Peijun Guo

Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.

If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.


Please login with a confirmed email address before reporting spam

Posted: 8 years ago Nov 16, 2016, 3:45 p.m. EST
Dear Peijun Guo,

It seems that I am solving similar problem to yours.

Can you help me with periodic bc? What k-vector should we put into Floquet periodic bc? The k-vector of the wave or of the grating?

I will be very grateful for your help!

Regards,
Eugene
Dear Peijun Guo, It seems that I am solving similar problem to yours. Can you help me with periodic bc? What k-vector should we put into Floquet periodic bc? The k-vector of the wave or of the grating? I will be very grateful for your help! Regards, Eugene

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.