Re: gEDA-user: Compiling MMI (electromagnetic simulator)

[Daniel Nilsson <daniel@xxxxxxxxxxxxxxx>]

On Sun, Dec 12, 2004 at 09:54:14AM +0000, Karel Kulhavy wrote:
> On Mon, Aug 23, 2004 at 09:33:31PM -0400, Dan McMahill wrote:
> > On Sun, Aug 22, 2004 at 06:13:34PM +0000, Karel Kulhav? wrote:
> > > Hello
> > > 
> > > MMI promises to compute distributed paramteres of copper strips on
> > > PCB.
> > 
> > looks neat once it can be built.  I've started and found some issues
> > with the build system.  Haven't fixed them all yet...
> > 
> > 
> > > I am lured by an idea of computing how many picoforad 1cm^2 of PCB trace on my
> > > 1.5mm FR-4 board makes. 
> > 
> > try out mcalc.sf.net to find impedance (sqrt(L/C)) and velocity (1/sqrt(LC)) of
> > your line and then solve for L and C.
> 
> Yes it works thanks.
> 
> > 
> > Thats useful for lines which are relatively long compared to their width.
> > for a simple parallel plate thing like what you have, you can 
> > 
> > a)  note that 1cm is a good bit more than 1.5 mm so just use C = eA/d
> >   (e = permitivitty of FR4 which is around 4.8x free space permitivitty)
> >   (A = area)
> >   (d = distance)
> > 
> > or 
> > 
> > b)  use something like fastcap if you want a more accurate field solution.
> 
> Don't you know where to download it's files?
> I didn't find it on freshmeat and opencollector.

Here's a good collection of links (including fastcap):

http://www.fastfieldsolvers.com/links.htm

What problem are you trying to solve ?

-- 
Daniel Nilsson