There shouldn't be a lower impedance issue, because from 150 kHz up the LISN is very close to 50 ohms. And once the LISN coil impedance is well above 50 ohms, the measured LISN impedance should be 50 ohms in parallel with the bleeder resistor, which is essentially 50 ohms. The only affect is if there is a parasitic that tanks with the coil to lower the total impedance to something closer to 50 ohms. That shouldn't be the case down the road if not when acquired, unless the LISN is damaged. So there really shouldn't be an issue here. Also, not familiar with modern VNAs (my HP 4195A has a max output of 15 dBm, or 122 dBuV across 50 ohms), but if I were using a signal generator and a spectrum analyzer, I could use quite high potentials (3 volts or more) and very flat current probe with say 0.1 or 1 ohm transfer impedance, to get numbers well above my noise floor, and a current probe with flat and low transfer impedance is very accurate because the value depends not on the construction of the probe but on the loading resistance, which is much easier to get to a specific value, just like the 50 ohms of the LISN has been noted in this thread to not be part of the LISN construction, but the load placed on it by a spectrum analyze or a dummy load of great precision. And the spectrum analyzer as a load must have at least 10 dB internal or external attenuation selected in order to give assurance that it looks like 50 ohms.
Ken Javor Phone: (256) 650-5261 > From: "T.Sato" <vef00...@nifty.com> > Reply-To: "T.Sato" <vef00...@nifty.com> > Date: Tue, 12 Sep 2017 21:58:54 +0900 > To: <EMC-PSTC@LISTSERV.IEEE.ORG> > Subject: Re: [PSES] LISN Calibration Measurement Uncertainty > > On Mon, 11 Sep 2017 16:32:09 +0000, > Mac Elliott <00000a115b29e815-dmarc-requ...@ieee.org> wrote: > >> We are interested in doing some in-house LISN calibrations (impedance >> verification only using network analyzer) and need to develop an uncertainty >> budget. >> Does anyone happen to have a budget you could share with us? We will go >> through the exercise of calculating ourself but if there is one out there >> would appreciate it if you could share. > > I think the major contributions would be: > > o network analyzer (VNA?); > o calibration jig which will be required to connect coax to the LISN > terminals. > > Other possible contributions such as resolution and repeatability may also > need to be considered, even if they are relatively minor. > > > For lower impedance, network analyzers may have relatively large impedance > measurement uncertainty: > > > http://www.keysight.com/main/editorial.jspx?cc=ES&lc=spa&ckey=1000002148:epsg: > faq&nid=-11143.0.00&id=1000002148:epsg:faq > > Regards, > Tom > > -- > Tomonori Sato <vef00...@nifty.com> > URL: http://t-sato.in.coocan.jp > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. To post a message to the list, send your e-mail to > <emc-p...@ieee.org> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used > formats), large files, etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <sdoug...@ieee.org> > Mike Cantwell <mcantw...@ieee.org> > > For policy questions, send mail to: > Jim Bacher: <j.bac...@ieee.org> > David Heald: <dhe...@gmail.com> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
