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Re: gEDA-user: Compiling MMI (electromagnetic simulator)
On Sun, Aug 22, 2004 at 06:13:34PM +0000, Karel Kulhav? wrote:
> MMI promises to compute distributed paramteres of copper strips on
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.
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)
b) use something like fastcap if you want a more accurate field solution.