Hi, Cody my first thought is that you can make the trace short to avoide the resonance appearing in your intrested frequency range. But please make sure length is till much bigger than width. thanks and regards Helen On 9/5/07, codymiller@xxxxxxxxxx <codymiller@xxxxxxxxxx> wrote: > > All, > > I am trying to measure the characteristic impedance of a strip line > trace, using a VNA. I would like to determine the frequency at which the > trace becomes very lossey. I am using a formula found in the Agilent > Impedance Measurement Handbook page 5-23. > http://cp.literature.agilent.com/litweb/pdf/5950-3000.pdf > > The method requires S11 of the transmission line open as well as S11 > with it shorted. > > |Zo| =3D sqrt(|Zopen|*|Zshort|) > > The method seems to work except I get some resonance at different > frequencies where the impedance increases significantly. The frequencies > of these resonants changes with different lengths of PCB trace. > > Can anyone recommend a different method for measuring characteristic > impedance over frequency? > > Thanks, > Cody Miller > codymiller@xxxxxxxxxx > ------------------------------------------------------------------ > 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 technical documents are available at: > http://www.si-list.net > > 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 technical documents are available at: http://www.si-list.net 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