measure of a frequency selective surface

[blackbird4280]

Hi,
I have a question about a measurement I did on some frequency
selective surfaces.
I measured their transparency and found a perfect match with respect
the simulated behavior in CST Microwave Studio: there is a
transparency window around several frequency (the fundamental
frequency f0 and the grating lobes).
I also measured their reflection in order to compare it with the
reflection by a metal plate of the same size: the FSS reflects at any
frequency like a metal plate and obviously there is no reflection at
the frequency f0 (actually there is just a very weak reflection).
There is an unexpected behavior around the grating lobes, because at
that frequencies the FSS is transparent, but it reflects just like a
metal plate.
Can anyone explain me this? Thank you!

 

[Rene Tschaggelar]

Hi,
I have a question about a measurement I did on some frequency
selective surfaces.
I measured their transparency and found a perfect match with respect
the simulated behavior in CST Microwave Studio: there is a
transparency window around several frequency (the fundamental
frequency f0 and the grating lobes).
I also measured their reflection in order to compare it with the
reflection by a metal plate of the same size: the FSS reflects at any
frequency like a metal plate and obviously there is no reflection at
the frequency f0 (actually there is just a very weak reflection).
There is an unexpected behavior around the grating lobes, because at
that frequencies the FSS is transparent, but it reflects just like a
metal plate.
Can anyone explain me this? Thank you!

What exactly is the problem to understand ? As long
as Maxwell is satisfied...
I'd need to know more in order to tell more.

Rene