I have seen similar values elsewhere, but always in the context of a one-meter separation measurement. One would expect much worse with antennas farther apart.
Not coincidentally, the original use of unlined chambers for radiated work was with antennas one-foot from the test sample. Obviously even less effect there, making unlined chambers practical and useful in their original application. -- Ken Javor Ph: (256) 650-5261 From: Ralph McDiarmid <[email protected]> Reply-To: <[email protected]> Date: Wednesday, October 9, 2024 at 5:37 PM To: <[email protected]> Subject: Re: [PSES] Technical musings I was hoping John would join the discussion at some point. 😊 I recall eigenvalue and eigenvector, but the term eigentone is a new one for me. Don White Consultants wrote, “Pragmatically, it develops that the worst-case situations are likely to result in no more than about 20 dB peak-to-peak variation” That was in the context of a metal box with no RF absorbers. Ralph From: John Woodgate <[email protected]> Sent: October 9, 2024 1:18 PM To: [email protected] Subject: [PSES] Technical musings Reply to Derek @ LF Research, because his post is labelled as SPAM. Yes, adding OATS is always healthy.😉 Is there an accepted explanation for the '3 m excess'? The published results are consistent with the field being diffuse (that term is from acoustics: I'm not sure how widely it's used in EMC circles), i.e the resultant of a large number of direct, reflected and diffracted rays. It is hardly surprising: a cuboid space is 'ideal' for producing a diffuse field above 'eigentone' wavelengths. This might create at least a 3 dB increase over 'inverse square' and maybe more. I suppose things get complicated at wavelengths that cannot be called 'short'. Has anyone tried a spherical chamber? If that's too difficult, a 'quartic sphere [(x,y,z)^4 = r^4, like a Swedish traffic circle] has noticeably rounded corners and edges, so might be close enough for a useful improvement. -- OOO - Own Opinions Only Best Wishes John Woodgate Keep trying Virus-free.www.avg.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 [email protected] All emc-pstc postings are archived and searchable on the web at: https://www.mail-archive.com/[email protected]/ Website: https://ewh.ieee.org/soc/pses/ Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators: Mike Sherman at: [email protected] Rick Linford at: [email protected] For policy questions, send mail to: Jim Bacher at: [email protected] To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1 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: https://www.mail-archive.com/[email protected]/ Website: https://ewh.ieee.org/soc/pses/ Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators: Mike Sherman at: [email protected] Rick Linford at: [email protected] For policy questions, send mail to: Jim Bacher at: [email protected] To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1 - ---------------------------------------------------------------- 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: https://www.mail-archive.com/[email protected]/ Website: https://ewh.ieee.org/soc/pses/ Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators: Mike Sherman at: [email protected] Rick Linford at: [email protected] For policy questions, send mail to: Jim Bacher: <[email protected]> _________________________________________________ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
