Hi Bob, You could try the differential embedded coplanar waveguide in the Polar Si6000, you would need to set the "D" dimension large so the coplanar grounds were out of the sphere of influence... www.polarinstruments.com/products/cits/Si6000.html Kind regards Martyn Gaudion www.polarinstruments.com At 10:51 09/12/2002 -0600, you wrote: > I am trying to calculate the differential impedance of two pcb >traces (ie a balanced pair) when they are routed in the area of a pcb with >NO power/gnd plane to use as a reference. The available tools that I have >access to only treat the cases that include a reference plane; ie >microstrip, stripline, edge-coupled traces over a plane, etc. I also >tried digging into a few of my old ElectoMagnetics textbooks, but those >formulas for parallel-plate transmission lines make assumptions that >handle only the case in which the plate width >> separation distance. I >am having trouble finding a transmission line model that reflects pcb >trace geometries. > > Any helpful information, formulas, links to websites, etc., would >be greatly appreciated. > >Thanks in Advance, > >Bob Tarasewicz >Westell, Inc. >ph 630-375-4461 >btara@xxxxxxxxxxx > >------------------------------------------------------------------ >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: >//www.freelists.org/webpage/si-list > >For help: >si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > >List archives are viewable at: > //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: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //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