From: Lawrence Butcher ([email protected])
Date: Tue May 09 2000 - 17:40:09 PDT
It's fun to hear more about the 20H rule.
It is nice to have constant things in life.
But progress now and then doesn't hurt, either.
I wonder, has anyone considered taking some copper tape and wraping
it around the perimeter of a board? The midline of the tape should
be at the board edge. Half of the tape should be pressed onto the
bottom of the board, the other half of the tape pressed to the top.
It would make capacitive contact to the top and bottom layers of the
board.
It seems intuitive to me that this copper tape should have MORE effect
than any fancy dadoing of the ground plane.
In the unlikely event that the measurement shows a benefit from having
this tape, then we should try the PC board equilvalent.
Instead of setting the power plane back 20H, I suggest that we set it
back far enough to let there be another trace around the outside on
the power layer. That trace should be hooked to the above and below
ground planes every 4 via diameters or so.
This could be called the club sandwich variation of the 20H rule.
This is an obvious experiment. Would it help? It would be fun to know.
I propose that those who believe in the 20H rule try this, and report back.
Lawrence
>
> > -----Original Message-----
> > From: [email protected]
> > [mailto:[email protected]]On Behalf Of Mary
> > Sent: Friday, May 05, 2000 2:50 PM
> > To: [email protected]
> > Subject: RE: [SI-LIST] : May 9th Presentation: "Radiation from Edge
> > Effects in Printed Circuit Boards (PCBs)"
> >
> >
> > This is a fascinating discussion group. My background is in the
> > microwave circuits area, so I can't be sure how much of what is
> > posted here is correct. However, I have come to the conclusion
> > that most of the information posted concerning the 20H rule was
> > bogus.
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