HFSS plot poynting vector

[yefeng]

Hi, everybody,
I am using a plane (-z direction) to launch on a pec. The size of the pec is just the same as the airbox. And I set both x and y direction to be periodic boundaries.
When I plot the poynting vector in the airbox, I found that both above and below sides have poynting. And they are almost the same as large, about 1.33*10^-3W/m^2, while opposite directions.
So the energy flowing out of the airbox will be 2*1.33*10^-3W/m^2. While the incident wave causes about 1.33*10^-3W/m^2 (1/2*1*1/377= 1.33*10^-3) into the airbox.
How could this be possible that the energy flowing out of the box is larger than into the airbox?
Where do I make errors?
Thanks !
The picture is what I did.

 

[yefeng]

Can anyone help?

 

[PlanarMetamaterials]

Hi yefeng,

I am currently investigating the phenomenon myself, in HFSS 13. Have you meshed your integration surface very finely? Have you manually computed ExH*?

I'll post if I find anything conclusive...

 

[eztucker]

I am still confused about how you set up your model. Did you use a plane wave excitation? That should apply a plane wave across the whole geometry all in the same direction. Or did you use a floquet port? In the later case, I don't think you should have anything on the other side of the PEC, right?

Anyhow, I have read elsewhere that you can get unphysical quantities for power exiting your geometry if you didn't mesh certain boundaries well enough compared to others. I am work on a similar problem, so feel free to message me if you want share info!