Dear David, Thank you very much for the information. I will read it after I reset my password with the IEEE. Our foam supplier gave me two pieces of polyethylene foam (24"x24"x2") this morning. One is 2 lb density and the other one is 4 lb density. According to his explanation, Styrofoam is expanded polystyrene (EPS) and it does not support heavy weight. He has no idea of the dielectric constant. My question is: does any one have dielectric constant information for Styrofoam and polyethylene? Best regards, Grace
On 1/28/08, Britton, David A (EMC Vancouver) <[email protected]> wrote: Hi all, Some of my HP compatriots did a paper on styro tables back in 2002. The title of the paper is "More on field perturbations due to accessories used in radiated emissions tests." Go to www.ieee.org and look in IEEExplore (note all IEEE EMC members now have full access to symposia docs!) A direct link to the paper is http://ie explore.ieee.org/search/srchabstract.jsp?arnumber=1032660 <http://ieeexplore.ieee.org/search/srch bstract.jsp?arnumber=1032660&isnumber=2 168&punumber=8028&k2dockey=1032660@ieee nfs&query=%28%28%28%28blankenship%29%3C n%3Emetadata%29%29%3Cand%3E%28%28emc%29%3Cin%3Emetadata%29%29&pos=0> &isnumber=22168&punumber=8028&k2dockey= 032660@ieeecnfs&query=%28%28%28%28blank nship%29%3Cin%3Emetadata%29%29%3Cand%3E%28%28emc%29%3Cin%3Emetadata%29%29&pos=0 We currently use Styro tables with cardboard tops in both RE and RI. They are solid block versions that can hold several hundred pounds. We replace the cardboard every 2 years or so. Regards, David Britton IEEE EMC Society Oregon and SW Washington Chapter Secretary 2007 http://ewh.ieee.org/r6/oregon/emc/Chapter_Home.htm From: [email protected] [mailto:[email protected]] On Behalf Of Scott B. Lacey Sent: Saturday, January 26, 2008 5:52 AM To: Price, Edward Cc: [email protected] Subject: RE: Table for Measuring Emission for Desktop Equipment Ed, It is common practice among automotive enthusiasts (car nuts) to place sheets of cardboard underneath cars stored for a long time in garages to absorb moisture vapors coming up through concrete floors. The cardboard is replaced periodically with fresh sheets. Scott Lacey On 25 Jan 2008 at 15:22, Price, Edward wrote: > > I don't have any data on cardboard, but it seems to me that the > cardboard should be just about the same humidity as the air > next to it. The cardboard box material is relatively thin, and > permeable to the air. Is there something I don't understand > about the cardboard; will it somehow extract or concentrate > moisture from the surrounding air? > > Ed Price > [email protected] WB6WSN > NARTE Certified EMC Engineer & Technician > Electromagnetic Compatibility Lab > Cubic Defense Applications > San Diego, CAUSA > 858-505-2780 (Voice) > 858-505-1583 (FAX) > Military & Avionics EMC Is Our Specialty > > > > From: [email protected] [mailto:[email protected]] On Behalf Of Daniel Roman > Sent: Thursday, January 24, 2008 6:05 AM > To: [email protected] > Subject: RE: Table for Measuring Emission for Desktop Equipment > If you can't use wood for a table, why would cardboard be ok? I would imagine that it would > alsoabsorb moisture from the air and cause attenuation at high frequencies. > > Regards, > > -- > Dan Roman, N.C.E. > Regulatory Engineer > Dialogic, Inc. > 1515 State Rt. 10 > Parsippany, NJ 07054-4538 > *mailto:[email protected] > (Voice: +1 973-967-6485 Fax: +1 973-967-6262 > Internet: http://www.dialogic.com > > > > From: [email protected] [mailto:[email protected]] On Behalf Of Price, Ed > Sent: Thursday, January 24, 2008 8:53 AM > To: [email protected] > Cc: [email protected] > Subject: RE: Table for Measuring Emission for Desktop Equipment > I am fortunate to have our company's shipping department > located immediately next to my lab. I often use empty cardboard > boxes to build non-conducting platforms. It's surprising how > much weight a taped box can support. > > There are several densities of urethane foam, but there is also a > white foam made from polyethylene (or maybe polystyrene). This > stuff is so strong that you can't hardly make a dent in it with > your thumb. Finally, there is the foam which is used for foam-in- > place packing. This stuff is poured into a box like a bubble-bath, > and then cures to a hard foam. Fill an empty cardboard box with > this foam, and you can get a very tough support structure. > > > - ---------------------------------------------------------------- This message is from the IEEE Product Safety > Engineering Society emc-pstc discussion list. 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Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] 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] 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 [email protected] 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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
