It would be completely correct to say that the 51.5 dB factor is dB above one ohm, which is the difference in magnetic and electric field units.
Ken Javor Phone: (256) 650-5261 From: John Woodgate <j...@woodjohn.uk> Reply-To: John Woodgate <j...@woodjohn.uk> Date: Thu, 17 Jan 2019 22:11:50 +0000 To: <EMC-PSTC@LISTSERV.IEEE.ORG> Subject: Re: [PSES] CISPR11 Rad Magnetic Field Emissions Limits To fill in, that 51.5 dB = 375.84 numerically and comes from the impedance of free space, 120*¼ = 376.99 ohms. which is actually 51.5266 expressed in 'decibels'. Actually, expressing an impedance in 'decibels' is a illegal operation 'but it works, so why bother?'. Best wishes John Woodgate OOO-Own Opinions Only J M Woodgate and Associates www.woodjohn.uk <http://www.woodjohn.uk> Rayleigh, Essex UK On 2019-01-17 21:57, Ken Javor wrote: > Re: [PSES] CISPR11 Rad Magnetic Field Emissions Limits You are making too > much of it. If the limit is in terms of dBuA/m, you use the loop magnetic > field antenna factor, which is 51.5 dB less efficient than the loop electric > field antenna factor. Of course, this is based on a far field assumption, and > that is all you have available. But the magnetic field antenna factor is > fundamental; it is the loop electric field antenna factor that is based on the > FF assumption, so you need not worry at all. > > No worries! > > Ken Javor > Phone: (256) 650-5261 > > > > > From: "Kunde, Brian" <brian_ku...@lecotc.com> <mailto:brian_ku...@lecotc.com> > Reply-To: "Kunde, Brian" <brian_ku...@lecotc.com> > <mailto:brian_ku...@lecotc.com> > Date: Thu, 17 Jan 2019 21:27:15 +0000 > To: <EMC-PSTC@LISTSERV.IEEE.ORG> <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> > Conversation: CISPR11 Rad Magnetic Field Emissions Limits > Subject: [PSES] CISPR11 Rad Magnetic Field Emissions Limits > > Reference CISPR11/EN55011:2016 version. > > If you are an expert at the Radiated Emissions test from 150Khz -30Mhz for > Class A Group 2 equipment, I could really use your help. > > I haven¹t done this test in over 25 years. I refurbished our Active Loop > antenna and placed it 10 meters from the EUT. I believe the data values read > by our receiver is dBuV/m. However, the limits as it appears in Table 10 are > in dBuA/m. How do I convert? > > I have an old 1999 copy of this standard that shows the limits with the exact > same frequency ranges but the limits are in dBuV/m. Do I just use these > limits or do I have to somehow convert the receiver data to dBuA/m. > > I know a straight conversion between dBuV/m and dBuA/m can be difficult > because above 4Mhz we are in the far-field, but below that we are getting into > the near field. And the impedance calculation can be difficult to obtain. > > Am I making too much of this or just take a simple conversion based on the > differences between the two versions of the standard? > > Thanks for the help. > > The Other Brian > > > LECO Corporation Notice: This communication may contain confidential > information intended for the named recipient(s) only. If you received this by > mistake, please destroy it and notify us of the error. Thank you. > - > ---------------------------------------------------------------- > > 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> <mailto: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) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <sdoug...@ieee.org> <mailto:sdoug...@ieee.org> > Mike Cantwell <mcantw...@ieee.org> <mailto:mcantw...@ieee.org> > > For policy questions, send mail to: > Jim Bacher <j.bac...@ieee.org> <mailto:j.bac...@ieee.org> > David Heald <dhe...@gmail.com> <mailto: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) <http://www.ieee-pses.org/list.html> > 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) <http://www.ieee-pses.org/list.html> 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>
