[SI-LIST] : NOTE 03/30/98 16:24:58

rbmccammon@mmm.com
Mon, 30 Mar 1998 16:29:48 -0600

scarp@sonnetusa.com (Shawn) wrote:

>Good question. I tried it out, and added a twist that I didn't
>consider before--the physical thickness of the conductors.

>With physically thick metal models, you get a 50 ohm
>system with G =3D S =3D 12 mils (I had previously reported 13 mils,
>but that was with a physically thin metal model applied to the EM
>simulator).

>With a large ground plane (microstrip-like configuration) you reach
>a 50 ohm system with a signal line width of just under 10 mils
>(considering
>the thickness of the metal). If you used this value for your signal an=
d
>finite ground conductor widths, you'd end up with a 59 ohm system -- o=
ff
>by >almost 20%.

And might that variation be less than the variation due dielectric cons=
tants?
=