Not an expert on that standard, but technically speaking. If indeed both 300 meter and 3 meters are both in the far field of the transmitting antenna, then the scaling is as 20 log (distance ratio). That would yield a 40 dB relaxation, so your first answer is correct.
I cannot think of a case where the scale factor is 40 log (distance ratio) over such a large ratio. In order to provide a more useful answer, the transmit frequency and antenna physical size and gain and type would be useful. Ken Javor Phone: (256) 650-5261 From: Youngsik Kim <fs741fs...@gmail.com> Reply-To: Youngsik Kim <fs741fs...@gmail.com> Date: Thu, 6 Apr 2023 11:32:20 +0900 To: <EMC-PSTC@LISTSERV.IEEE.ORG> Subject: [PSES] Question for FCC Part 18 RE test? Hi Experts According to FCC part 18.305 FIELD STRENGTH LIMITS, a test article of Any type unless otherwise specified has a measurement distance of 300 meters, but I want to measure it at a distance of 3 meters because I need to measure it in a chamber. In this case, what is the limit at 3 meters? If we use Any non-ISM frequency, the measurement distance is 300 meters and the limit value is 15 uV/m, We have a limit of 63.5 dBuV/m when measuring at 3 meters. However, other laboratories apply a limit of 103.5 dBuV/m. Depending on the RF power of the test device, can I use a 40 log instead of a 20 log conversion? Is the conversion different depending on the power of the test device? Translated with www.DeepL.com/Translator <http://www.DeepL.com/Translator> (free version) Best Regards - ---------------------------------------------------------------- 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 Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) <http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org> David Heald <dhe...@gmail.com> 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 <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html 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: Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com> _________________________________________________ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
