Pat:
It might just be the name you like best depends on your experience. Considering that most chambers depend on rotating or oscillating conductive mechanical structures, you might think of the paddles acting like big blades in a mixer or stirrer. A waveguide guy might be thinking more in terms of propagation modes. I'm not very comfortable with "mode stirred", possibly because that term was applied to microwave ovens and I don't think the amount of "stirring" they had was enough to really change from one mode to the next, and "partial mode stirred" is too big for a name tag. The name I prefer is a Reverberant Chamber. You can take advantage of the multiple reflections in a chamber (actually enhancing the reflections through the use of the moving mechanical structures) to achieve higher E-fields. This allows you to get higher E-fields for a test like RS103 than you could get using traditional methods. In effect, you can get higher fields with less money spent on an amplifier. The down side (isn't there always a down side to slick solutions) is that you have to spend a finite amount of time at a given frequency to allow the reflections to have a reasonable amount of variation in order to ensure you will get a good additive combination of room reflections). So practically, this implies a stepped frequency sweep, with dwells at each frequency on the order of several seconds to several minutes. And of course, there is a lower frequency limit based on your ability to change reflections within a chamber with the amount of moving conductive surfaces in relation to the volume of the chamber. Practically, we hit that limit around 100 MHz or so (depending on how much money you spend on your chamber). It's a messy calculus; facility money, equipment money and test time. Ed Price WB6WSN Chula Vista, CA USA From: Pat Lawler [mailto:pat.law...@verizon.net] Sent: Sunday, April 28, 2013 7:38 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Mode-stirred, Mode-tuned, Reverb - what's the difference? All, Over the years, I've come across pictures of test chambers with descriptions such as mode-stirred, mode-turned, and reverberation. They seem to look similar, with metal walls and rotating metal paddles. Do these names reference the same basic design, or are they different animals? Which ones are used for which type of RF immunity test? Thanks, Pat Lawler Teset engineer - ---------------------------------------------------------------- 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>
