No experience with Ethernet per se, so this is a very general comment. It sounds as if the emissions are common mode. If so, they may not have anything to do with the Ethernet itself, the Ethernet may be a fortuitous conductor. I would check this using a current probe around the cable, with and without Ethernet traffic. If there is little or no difference, it is ground bounce in the printed circuit board driving conducted emissions onto the Ethernet. Then you have to look at suppressing emissions from that source.
From: "McBurney, Ian [Allen & Heath UK]" <ian.mcbur...@allen-heath.com> List-Post: emc-pstc@listserv.ieee.org Date: Fri, 17 Jun 2005 12:17:17 +0100 To: <emc-p...@ieee.org> Subject: ethernet radiated emissions Dear colleagues; Can anyone advise me how to reduce the radiated emissions from a 100 base-T Ethernet port with a UTP cable connected to below the EN55022 class B limit? At the moment I am 20dB above the limit at 33MHz. Using STP only reduces the emissions by 6dB. Thanks in advance; Ian McBurney. Allen & Heath Limited. email: ian.mcbur...@allen-heath.com ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
