Arpad, This two T-lines vs one T-line mode distinction is confusing to me. What makes the two T-lines support even or odd kind of modes? and the one T-line support the TEM kind of modes? Is it not possible to have TEM kind of mode propagation in a two T-line system? How would you define a MODE when it is meant even or odd mode ? and when it is meant TEM mode? Thanks, Sainath ----- Original Message ----- From: "Muranyi, Arpad" <arpad.muranyi@xxxxxxxxx> To: <si-list@xxxxxxxxxxxxx> Sent: Monday, February 25, 2002 10:26 AM Subject: [SI-LIST] Re: Even mode, common mode, and mode conversion > > What may be confusing to some is that the word "mode" is used > in different ways in different contexts, both involving > transmission lines. > > So far most responses mentioned the even or odd mode, where > the signals of ***two*** T-lines go either in the same or the > opposite direction. > > The other usage of this word involves only one T-line (or > wave guide or optical fiber) and describes how the electro > magnetic waves propagate inside that line, one of the most > familiar mode being the TEM (Transverse Electro Magnetic) > mode. Don't confuse the two meanings of the word MODE! > > Arpad Muranyi > Intel Corporation > ================================================================= > > -----Original Message----- > From: Dima Smolyansky [mailto:Dima@xxxxxxxxxxxxxx] > Sent: Monday, February 25, 2002 9:54 AM > To: doug@xxxxxxxxxx; si-list@xxxxxxxxxxxxx > Subject: [SI-LIST] Re: Even mode, common mode, and mode conversion > > > > Doug: > > The distinction is subtle, and the two mode impedances are defined as : > - Differential mode impedance is impedance between two traces when the > traces are driven with differential stimulus > - Odd mode impedance is impedance of one of the traces when the traces are > driven with differential stimulus > > In practical terms, if you need to measure odd mode impedance with TDR > oscilloscope, you would simply drive the trace pair differentially and > measure one channel only (no waveform math). If you need to measure > differential mode impedance, you would drive the trace pair differentially > and subtract your voltage waveforms on the two channels, or add the > impedance waveforms, depending on how your scope operates. If your traces > are symmetric, then the differential impedance is simply twice the odd mode. > > We have an FAQ entry on our web site at > http://www.tdasystems.com/faq/faqTDR.htm#even_odd_modes. > > Thanks, > > =================== > Dima Smolyansky > TDA Systems, Inc. > 11140 SW Barbur Blvd., Suite 100 > Portland, OR 97219 > (503) 246-2272 > (503) 246-2282 (fax) > (503) 804-7171 (mobile) > www.tdasystems.com > > > > > ----- Original Message ----- > From: "Doug Brooks" <doug@xxxxxxxxxx> > To: <si-list@xxxxxxxxxxxxx> > Sent: Monday, February 25, 2002 9:31 AM > Subject: [SI-LIST] Even mode, common mode, and mode conversion > > > > > > Gurus, > > > > I've been following the thread on mode conversion and suspect I am not the > > only one with this question. Can someone explain, in layman's terms: > > > > The distinction between even mode and common mode? > > between odd mode and differential MODE (not to be confused with > > differential traces) > > > > And does the existence of differential traces add any complications to > > these distinctions? > > > > Thanks for bringing the dummies along with you! > > > > Doug Brooks > > > > > > ------------------------------------------------------------------ > > 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 > > ------------------------------------------------------------------ > 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