[quote author=Fu-Kwun Hwang link=topic=744.msg2796#msg2796 date=1221315645]
Frequency f=100MHz, so the wavelength= 3*10[sup]8[/sup]/10[sup]8[/sup]=3M
I believe the distance D between your conducting wire grid is much small than the wavelength.
I will assume the wire can behavior like a conducting plate. So I think it can stop most of the electromangetic field if those wire are very good conductors.
However, if the distance D become larger , than I do not think there is a simple formula available.

Are you doing some real project or this is just some test problem?
What is the source for your 100MHz vertically polarized electromagnetic wave?
What is the spatial distribution of the EM wave?

Dear Fu ,

    What I  want is to  shield  a large window from  incident FM  radiation. So ,I  would  like to  select ,from the  market , a suitable  wire - grid . Of course the dimensions d and D will be much smaller compared to wave - length . I would  like however ,to have a mathematical  formula on the attenuation that  will  be  achieved (in dB) to chose the  right  grid.
    The EM-wave spatial  distribution can be  assumed uniform .
    Are  there any lecture notes  related  to  the  subject ?? I would be  interested .

                                                                        Best Regards