Hi All, I just posted my Technical Tidbit for August, 2011. Be careful of the Power Over Ethernet injector you use, many will cause a radiated emissions failure. Not sure how they sell those units! See below:
Technical Tidbit - August 2011 Power Over Ethernet Injectors Can Affect Ethernet Radiated Emissions (High Frequency Measurement of 1000Base-T Ethernet Common Mode Currents) This month's Technical Tidbit describes how POE injectors and other Ethernet hardware can cause radiated emissions and how to check for problematic emissions right in your lab. Abstract: Power Over Ethernet (POE) has become widespread over the last few years and with that popularity a need has developed to add POE features to older Ethernet hardware. As a result, POE injectors have become available which inject DC power into an Ethernet connection. Some POE injectors significantly unbalance the Ethernet connection which results in common mode current on unshielded twisted pair (UTP) media. The resulting emissions from the UTP Ethernet cable can be significant. Three POE injectors were measured for their ability to generate common mode currents compared to a simple coupler. The experimental method used and results obtained are reported and contain a surprising result. The link to the article is: http://emcesd.com/tt2011/tt080111.htm The rest of nearly 200 articles and papers are linked from the main page at: http://emcesd.com Doug -- ------------------------------------------------------- ___ _ Doug Smith \ / ) P.O. Box 1457 ========= Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-----( ) | o | Email: [email protected] \ _ / ] \ _ / Website: http://www.dsmith.org ------------------------------------------------------- - ---------------------------------------------------------------- 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 <[email protected]> All emc-pstc postings are archived and searchable on the web at http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. 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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]>
