Ray, Pure mode VNA is not available, but pure mode TDNA is available with IConnect S-parameters and Tektronix TDS/CSA8200 TDR scope. For linear systems, however, "non-pure mode" VNA is as good as pure-mode. It is the non-linearity that makes a difference. Thanks, =================== Dima Smolyansky TDA Systems, Inc. 4000 Kruse Way Place Bldg. 2, Suite 300 Lake Oswego, OR 97035 (503) 246-2272 (503) 246-2282 (fax) IConnect(R) S-parameters version 3.5 is released! Request your quote for IConnect S-parameters now! www.tdasystems.com ----- Original Message ----- From: "Ray Anderson" <ray.anderson@xxxxxxxxxx> To: <si-list@xxxxxxxxxxxxx> Sent: Monday, April 04, 2005 1:23 PM Subject: [SI-LIST] PureMode VNA vs 4port VNA > Over the past year or so there has been a lot of discussion of > mixed-mode s-parameters, why they are useful, conversion of single-ended > to mixed mode, etc., etc.... > > As I understand it, mixed-mode s-parameters can be mesasured with a true > pure-mode VNA, with a 4-port VNA, or with a TDR (the last 2 methods > requiring mathematical post-processing of the measured data to create > mixed-mode s-parameter data). This post processing can occur either in > the instrument (with appropriate firmware) or after the fact in a > separate compute environment. > > Is it true that a true pure-mode VNA is still not available commercially > from any of the test equipment vendors? I wonder if anyone knowledgable > on the topic can comment in the practical differences a user should be > aware of when utilizing a 4-port VNA to measure mixed mode s-parameters > as opposed to the fabled pure-mode instrument. > > -Ray > > -- > Raymond Anderson > Senior Signal Integrity Staff Engineer > Product Technology Dept. > Package Engineering Group > Xilinx Inc. > > > ------------------------------------------------------------------ > 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 FAQ wiki page is located at: > http://si-list.org/wiki/wiki.pl?Si-List_FAQ > > List technical documents are available at: > http://www.si-list.org > > 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 FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org 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