This a different issue. While the field strength outside a simple loop (a model for the EUT) falls off predictably (but not as 1/r initially, as the field from the far side of the loop is not negligible), an EUT may require a much more complicated model, producing a field that falls off either more slowly or far faster than that of a simple loop.
I have studied this extensively for hearing loops, and I, and loop system manufacturers, have software to model the fields. One thing to watch out for is that if you try to plot the field strength in a place with a reinforced concrete floor, the reinforcement greatly reduces the field strength so the results are not meaningful. With best wishes DESIGN IT IN! OOO – Own Opinions Only www.jmwa.demon.co.uk J M Woodgate and Associates Rayleigh England Sylvae in aeternum manent. -----Original Message----- From: Cortland Richmond [mailto:[email protected]] Sent: Tuesday, February 28, 2017 2:14 AM To: [email protected] Subject: Re: [PSES] CORRECTION (wrong page) Passive Loop Emissions [General Use] On 2/27/2017 7:53 PM, Brent DeWitt wrote: > I think Ken's rational makes sense to me, since the 51.5 is derived from > 20*log(377). > > Sure, but now we're back to how close we are -- wavelengths -- to the emitter. 20*log(??) Low frequencies can be tricky, and I once had to double-check a test lab (not yours) results at a vendor, dragging the EUT out to their parking lot then wheeling a cart with a 6510 loop antenna, battery, AOR AR5000 receiver and RMS voltmeter [all mine] away to see how fast the signal dropped with distance compared to 3m. A fun time was NOT had, but I probably came across as a mad scientist. Again. At least no one ran out of a chamber... Cortland Richmond KA5S - ---------------------------------------------------------------- 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://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://www.ieee-pses.org/list.html (including how to unsubscribe) 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]> - ---------------------------------------------------------------- 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://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://www.ieee-pses.org/list.html (including how to unsubscribe) 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]>
