Because the Europeans think that is the right impedance to simulate a generic transmission line/antenna far from ground. I recall a Ph.D. with a Dutch name making the case that 150 Ohms for CDNs and the like was much better than 50 Ohms. One thing's for sure, on a qualitative basis. All the metallic vehicle-based specs and standards, aerospace (RTCA/DO-160 in the USA), military (MIL-STD-461 in the USA), and SAE-J551 (US?) should use a model that is lower impedance than that for simulating coupling to transmission lines far away from ground. This is evident by casual inspection of the equation for the characteristic impedance of a wire above a ground plane.
---------- >From: "Colgan, Chris" <[email protected]> >To: "'Emc-Pstc' (E-mail)" <[email protected]> >Subject: common mode immunity coupling units >Date: Tue, Nov 5, 2002, 10:38 AM > > > Please forgive my ignorance but can anyone tell me why above are designed to > give load and source impedances of 150 ohms? > > Cheers > > Chris Colgan > Compliance Engineer > TAG McLaren Audio Ltd > The Summit, Latham Road > Huntingdon, Cambs, PE29 6ZU > *Tel: +44 (0)1480 415 627 > *Fax: +44 (0)1480 52159 > * Mailto:[email protected] > * http://www.tagmclaren.com > > > > > ************************************************************** > Please visit us at www.tagmclaren.com > ************************************************************** > > The contents of this E-mail are confidential and for the exclusive > use of the intended recipient. If you receive this E-mail in error, > please delete it from your system immediately and notify us either > by E-mail, telephone or fax. You should not copy, forward or > otherwise disclose the content of the E-mail. > > Important Note: Any typographical, clerical or other error in this > communication is subject to correction without any liability on > the part of TAG McLaren Audio Limited. Any orders placed shall > be subject to acceptance by TAG McLaren Audio Limited on its > standard terms and conditions of sale which shall govern the > contract for the sale and purchase of the products ordered to the > exclusion of any other terms and conditions. > > TAG McLaren Audio Ltd > The Summit, 11 Latham Road > Huntingdon, Cambs, PE29 6ZU > Telephone : 01480 415600 (+44 1480 415600) > Facsimile : 01480 52159 (+44 1480 52159) > > ************************************************************** > Please visit us at www.tagmclaren.com > ************************************************************** > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: [email protected] > Dave Heald: [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > http://ieeepstc.mindcruiser.com/ > Click on "browse" and then "emc-pstc mailing list" > ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
