Re: gEDA-user: basic anti-EMI design q

[Dan McMahill <dan@xxxxxxxxxxxx>]

John Doty wrote:
> On Mar 26, 2006, at 4:46 PM, DJ Delorie wrote:
>
> > AFAIK, a mesh screen is as good as a solid plane if the mesh spacing
> > is less than the wavelength you're interested in.
>
> Should be quite a bit less. Power leakage goes like the square of the 
> hole diameter, so for 60 dB of shielding you want holes <0.001 
> wavelength or so. The details are complicated...

on the topic of shields... it is important to keep in mind that its not 
so much the area of a hole in the shield which will get you but rather 
the longest dimension.  a 1mil x 400 mil slot will probably hurt you 
more than a 20 mil x 20 mil hold

-Dan