Homebrew PCBs

I'm not expert on this but I saw (somewhere) a discussion of
capacitive coupling as an issue.  Especially at higher frequencies. 
  
Phil

--- In Homebrew_PCBs@yahoogroups.com, David Cureton <yahoo@d...> wrote:
> Hi Stefan,
>     It is my understanding that the copper islands or orphaned
copper is 
> removed to help with  EMC  (or do they call it FCC in the US) approval.
> 
> You are probably right in that a fat copper island will not do any
harm. 
> However at very high frequencies
> these isolated (in a DC sense) pieces of copper may just have the right 
> shape to form L's and C's that become resonant
> and hey - presto , you got yourself an antenna.
> 
> Although the chances of  a floating piece of copper  being resonant is 
> probably pretty slim, when designing for EMC you take all the free runs 
> that you can get
> 
> Also - When I say very high frequencies -  the signal cycle times do
not 
> have to be high frequencys - they just need fast transition times.
> 
> 
> Cheers,
> David
> 
> 
>