Hello SI-LIST, I would like to measure a differential structure with a network analyzer and have got the following questions: First I will measure single S-parameters which are afterwards converted mathematically to differential S-parameters as described by Bockelmann and Eisenstadt. 1) My VNA measurement system is connected to the DUT by cables and SMA connectors. I want to calibrate the network analyzer to the end of the cables using a standard SMA calibration kit, but I am not sure if this will be sufficient. Is there anything like a rule of thumb until which frequency it is tolerable to neglet the effect of the connectors and when I have to use a custom-designed calibration ? 2) Shall I design the traces between the differential DUT and the connectors as tightly- coupled transmission lines with a differential impedance of 100 Ohms or as two loosely- coupled traces with a single impedance of 50 Ohms each one ? In their books Bogatin and Johnson write that two loosely-coupled traces with 50 Ohms indeed have got a differential impedance of 100 Ohms and that tightly coupled traces are just used because of limited space on the pcb ? Furthermore I don`t really understand the appendix about coupled and uncoupled lines in the original article from Bockelmann and Eisenstadt. 3) Assuming that I will use coupled lines: Probably the differential impedance would reach the aimed 100 Ohms, but the single impedances would be somewhat higher than 50 Ohms. If I terminate the unused terminals with 50 Ohms SMA-termination plugs, can I neglet the imperfect termination or how should the terminatin look like ? How does the broadening / drift of the traces in the region of the sma connectors influence the measurement ? Can I neglet this effect ? Thank you, Matthias ____________________________________ Business Unit Geräteanschlusstechnik Technologielabor Dipl.-Ing. Matthias Bergmann Phoenix Contact GmbH & Co. KG Flachsmarktstraße 8 32825 Blomberg Germany Tel.: ++49 - (0) 5235 3-4 13 85 Fax: ++49 - (0) 5235 3-4 20 02 e-mail: mbergmann@xxxxxxxxxxxxxxxxxx Internet: www.phoenixcontact.com **************************************************************************************** 20.-24. April Hannover Messe 2009 Produkte und Lösungen für Ihren Erfolg - Besuchen Sie uns in Halle 9 Mehr Informationen unter http://www.phoenixcontact.de/hannovermesse **************************************************************************************** .................................................................. Phoenix Contact GmbH & Co. KG Sitz der Gesellschaft / registered office of the company: 32825 Blomberg USt-Id-Nr.: DE124613250 Pers. haftende Gesellschafterin / personally liable partner: Phoenix Contact Verwaltungs GmbH Amtsgericht Lemgo HRB 5273 / district court Lemgo HRB 5273 Kom. Ges. Amtsgericht Lemgo HRA 3746 / limited commercial partnership district court Lemgo HRA 3746 Geschäftsführer / Executive Board: Klaus Eisert Roland Bent Dr. Martin Heubeck Prof. Dr. Gunther Olesch Frank Stührenberg Dr. Heinz Wesch ___________________________________________________________________ Diese E-Mail enthält vertrauliche und/oder rechtlich geschützte Informationen. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtümlich erhalten haben, informieren Sie bitte sofort den Absender und vernichten Sie diese Mail. Das unerlaubte Kopieren, jegliche anderweitige Verwendung sowie die unbefugte Weitergabe dieser Mail ist nicht gestattet. ---------------------------------------------------------------------------------------------------- This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure, distribution or other use of the material or parts thereof is strictly forbidden. ___________________________________________________________________ ------------------------------------------------------------------ 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