Several years ago I was using a 3m FAR for pre-compliance measurements. They were using a giant BiLog antenna for the measurements. A constant factor was added to the measured values to arrive at the OATS value. The reason I stopped using their facility was because the data didn't correlate well with the 10m semi-anechoic chamber.
Regards Ravinder Ajmani HGST, a Western Digital company ravinder.ajm...@hgst.com ralph.mcdiar...@schneider-electric.com Sent by: emc-p...@ieee.org 10/16/2012 10:25 AM To EMC-PSTC@LISTSERV.IEEE.ORG cc Subject Re: [PSES] OATS vs FAR Radiated Emissions Limits Certainly radio frequency emissions measurement is far from an exact science, but that's probably just fine for what it is intended to do. Pass at one lab, fail at another seems to be a common theme, so there must be many variables at play. I've read that, depending on antenna size, 3 metre distance is within what is called the "near field" and if so, then I assume spectrum of radio emission wouldn't correlate well to what would be measured at 10m or 30m. _______________________________________________________________________________ Ralph McDiarmid | Schneider Electric | Solar Business | CANADA | Regulatory Compliance Engineering From: John Woodgate <j...@jmwa.demon.co.uk> To: EMC-PSTC@LISTSERV.IEEE.ORG Date: 10/16/2012 09:40 AM Subject: Re: [PSES] OATS vs FAR Radiated Emissions Limits In message <a60ff8a65589d24a98d82fafc6f0ac56062eb8c...@euroexcc1.sats.corp>, dated Tue, 16 Oct 2012, "Pawson, James" <james.paw...@echostar.com> writes: >These limits are lower than those for an OATS at 3m. Does anyone know >why the limits are lower and of a different characteristic? I'm >guessing something to do with the lack of reflective ground plane in >the FAR. > In principle, an attempt has been made to reconcile the limits applicable to the different measurement environments so that products with given emission levels produce at least similar test results (dB above or, preferably, below the limit) in each environment. The deliberations that resulted in these limits were long and very complex. -- OOO - Own Opinions Only. See www.jmwa.demon.co.uk The longer it takes to make a point, the more obtuse it proves to be. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - ---------------------------------------------------------------- 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://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <emcp...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com> ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. ______________________________________________________________________ - ---------------------------------------------------------------- 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://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <emcp...@radiusnorth.net> 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://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <emcp...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
