Re: automatic via grid (Re: gEDA-user: cc2420 (ZigBee) board)

[Hans Nieuwenhuis <hans@xxxxxxxxxxx>]

On Fri, 2 Jun 2006 18:46:07 -0500
"James Cotton" <peabody124@xxxxxxxxx> wrote:

> I think the problem with such an automatic approach would be that
> right now there isn't a good way to clear off unused copper islands
> from polygons, so that would reconnect them and make lots of little
> antennas all over your board.
> 

Leaving them floating as it is now would cause more problems IMHO. If you have an unconnected copper island next to a high frequency switching trace it would cause a capacitive coupling between the trace and the floating island. If that island has a natural resonance that lies near the switching frequency of the trace beneath it, then I have no idea what is going to happen. If that island is connected to ground I can treat it as a transmission line and calculate how big the gap between them needs to be to not being affected by the capacitive coupling.

Please correct me if I am wrong...

Regards,

Hans