Ryan, In High Speed Digital System Design by Stephen Hall, et al., Steven Mumbhy's emprical formulation is quoted as: er(freq)=6.32 - [2.17 + 0.168 x log10(freq in kHz)] x Vrsn where Vrsn is the volume content of the resin, which is approximated as 1-(thickness of the glass cloth/thickness of the dielectric layer) I didn't see the actual source and don't know how that relation was derived but according to the book, the relation was experimentally validated from 1kHz to 1Ghz. Hope that helps. Regards Ihsan On 1/17/07, ryansatrom <ryan.satrom@xxxxxxxxxxx> wrote: > Thanks for your feedback. Sometimes, living in the simulation world, > you forget the real-world effects of boards. > > Lee: Is there any way to predict this frequency dependency of er? > > Fred: Is the frequency dependence of R and G caused by the same issues > Lee is discussing (dielectric constant over frequency)? Are there any > other causes of this? > > (As a side note, the equation suggests R and G to be fixed in > frequency, while L and C are the frequency dependent values. I guess > that's why the lumped element model breaks down and models are more > accurately viewed as distributed full-wave EM models) > > Thanks again for the comments. > > Ryan > > ------------------------------------------------------------------ > To unsubscribe from si-list: > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > > or to administer your membership from a web page, go to: > http://www.freelists.org/webpage/si-list > > For help: > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > > > List technical documents are available at: > http://www.si-list.net > > List archives are viewable at: > http://www.freelists.org/archives/si-list > or at our remote archives: > http://groups.yahoo.com/group/si-list/messages > Old (prior to June 6, 2001) list archives are viewable at: > http://www.qsl.net/wb6tpu > > > ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: http://www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: http://www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu