Steve, I suppose your message was to address my questions to Arpad. There are 3 questions and I'm not clear which one is addressed. Is it possible to say few simple words about each question separately? Thanks, Sainath ----- Original Message ----- From: "Steve Corey" <steve@xxxxxxxxxxxxxx> To: <si-list@xxxxxxxxxxxxx> Sent: Tuesday, February 26, 2002 7:20 AM Subject: [SI-LIST] Re: Even mode, common mode, and mode conversion > > Sainath -- I will give you the short answer, and refer you to the texts > for the long answer. The even and odd modes are TEM modes, or at least > quasi-TEM. TEM vs. higher order modes describes the field distribution > across a single transmission line or waveguide structure. Quasi-TEM is > a basic assumption of the transmission line theory on which we rely, > including characteristic impedance and RLGC matrices. It requires that > to first order, no field has a component in the direction of > propagation. I usually rely on "Analysis of Multiconductor Transmission > Lines" by Clayton R. Paul when I have questions of this sort. > > The higher order modes are significant to transmission line theory for > the most part in that we try to make sure they don't exist, since they > each propagate with their own velocities and make a mess of our nice > clean square waves. Any E/M text with a waveguide section will describe > the physics behind this. > > On the other hand, all TEM modes propagate. Analysis of the different > TEM modes supported on a multiconductor transmission line structure is > from my perspective more of a mathematical tool for breaking down a > system into its most basic components. In the case of even/odd, this > has a very practical application in differential signaling, but once we > step outside of the symmetric coupled two-line regime, the math gets > pretty complicated to try and define signaling schemes which coincide > with any particular modes. > > So-called "full-wave" analysis, which essentially means "non-TEM > analysis" for our purposes, is necessary for situations where we can't > count on quasi-TEM assumptions. These situations occur when we step > outside of the strict geometries of uniform transmission lines, or into > certain loss regimes. Again, I would refer you to the book by Clayton > R. Paul. > > -- Steve > > ------------------------------------------- > Steven D. Corey, Ph.D. > Time Domain Analysis Systems, Inc. > "The Interconnect Modeling Company." > http://www.tdasystems.com > > email: steve@xxxxxxxxxxxxxx > phone: (503) 246-2272 > fax: (503) 246-2282 > ------------------------------------------- > > > Muranyi, Arpad wrote: > > > To all, > > > > Sainath addressed his question to me, but I am going on vacation > > and don't have the time to answer it. Could someone please > > give him a good explanation to his questions? Thanks, > > > > Arpad > > ================================================================= > > > > -----Original Message----- > > From: sainath@xxxxxxxxxxxxx [mailto:sainath@xxxxxxxxxxxxx] > > Sent: Monday, February 25, 2002 11:18 AM > > To: si-list@xxxxxxxxxxxxx > > Subject: [SI-LIST] Re: Even mode, common mode, and mode conversion > > > > > > > > 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 > >>================================================================= > >> > > ------------------------------------------------------------------ > > 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