Thanks for pointing that out. Not too often we get mentioned together :-D What you say is true of course, but my opinion is still that in practical EMI measurements with typical EMI antennas a free-space AF is the best choice whether you measure from 3m or 10m distance.
Ari Honkala >-----Original Message----- >From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf >Of ext Ken Javor >Sent: 29. helmikuuta 2008 10:12 >To: Untitled >Subject: Re: Free Space Antenna Factor > >Mr. Honkala violates the fundamental rule of physics >annunciated by Albert >Einstein: "Everything should be made as simple as possible, but not >simpler." > >While the antenna factor is by definition the ratio of voltage >delivered at >the antenna terminal relative to illuminating electric field, it is the >nature of the illuminating electric field itself which is >different between >three, ten, thirty meters and free space. Free space implies a >plane wave >illumination, the other separations more or less approximate free space >illumination according to frequency and antenna geometry, >because antenna >factor is measured using two identical antennas a fixed >distance apart. The >three, ten or thirty meter antenna factor approaches the free >space factor >when the antenna physical size is small with respect to >separation, making >it look like the point source radiator of a plane wave. > >Ken Javor > >Phone: (256) 650-5261 > > >> From: <ari.honk...@nsn.com> >> Date: Fri, 29 Feb 2008 09:59:58 +0200 >> To: <emc-p...@ieee.org> >> Conversation: Free Space Antenna Factor >> Subject: RE: Free Space Antenna Factor >> >> Back to basics: >> Antenna factor is merely the ratio of E-field strength and >the voltage in >> antenna terminals. >> Therefore it is not related to any distance from source. >> >> It is related to distance from ground plane, but the >free-space AF gives a >> practical average value that is usable when a single figure >is used in >> emission test. >> >> Determination of AF in different ways means different errors in it. >> >> Ari >> >>> -----Original Message----- >>> From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf >>> Of ext John Woodgate >>> Sent: 29. helmikuuta 2008 9:44 >>> To: emc-p...@ieee.org >>> Subject: Re: Free Space Antenna Factor >>> >>> In message >>> <e2ceff6b0970a840bb7597dc31bec33003100...@esebe107.noe.nokia.co >> m>, dated >>> Fri, 29 Feb 2008, ari.honk...@nsn.com writes: >>> >>>> read the appendix 3 of the NPL paper. >>>> They state that " free-space antenna factor is appropriate for 3 m >>>> measurements". >>> >>> What is the context? I think it's a surprising statement if >it is said >>> to be applicable to all possible designs of antenna. >>> -- >>> OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and >www.isce.org.uk >>> For very important information, please turn over. >>> John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK >>> >>> - >>> ---------------------------------------------------------------- >>> 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 emc-p...@ieee.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...@ptcnh.net >> Mike Cantwell mcantw...@ieee.org >> >> For policy questions, send mail to: >> >> Jim Bacher: j.bac...@ieee.org >> David Heald: emc-p...@daveheald.com >> >> 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 emc-p...@ieee.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...@ptcnh.net > Mike Cantwell mcantw...@ieee.org > >For policy questions, send mail to: > > Jim Bacher: j.bac...@ieee.org > David Heald: emc-p...@daveheald.com > >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 emc-p...@ieee.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...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
