I have no knowledge of the rationale behind the 1/3/10 V/m limits, but I see a very big disconnect between the limits and the concept of any kind of hand-held transmitter. The fatal flaw can be found partly in the 1000-4-3 calibrated quiet zone, but much more obviously on the 1000-4-6 limit itself.
If the culprit were simply a nearby hand-held transmitter then the requirement to have a 1.5 meter square quiet zone would be tremendous overkill. Recall that when this requirement was levied almost no one had a facility capable of generating the required field uniformity, and such a facility runs several hundred thousand dollars to acquire. Meanwhile there were labs all over the civilized world capable of testing at much higher levels (at least 20 V/m and up to 200 V/m) but which couldn't meet the quiet zone requirement. Along the same lines, but much more obviously, 1000-4-6 is the extension of 1000-4-3 to lower frequencies. The limit is flat from 150 kHz to 80 MHz. The inescapable implication of that is a far-field illumination of a very long cable. In fact, the limit allows a start frequency higher than 150 kHz for cables of specified maximum lengths. So the concept at least below 80 MHz is high power broadcast transmissions. Since the limit is the same for 1000-4-3 and 1000-4-6 (the conducted limit "corresponds" to the radiated limit) I interpret that to mean the culprit must be the same. Certainly this would be true over the frequency band of broadcast television. While handheld radios or cell phones can also generate similar fields one would not control the entire 150 kHz to 1 GHz band in the manner of 1000-4-3 and 1000-4-6 based simply on hand-helds. Ken Javor > From: "Chris Wells" <[email protected]> > Date: Wed, 6 Aug 2003 06:47:37 -0400 > To: "'IEEE EMC-PSTC GROUP'" <[email protected]> > Subject: Re: Why 3 and 10V/m? > > Ian - I do not know the specific metric that defines 3 and 10V/m but it is > tied to the expected exposure limits in these enviroments. > In power distribution gear in the USA you can find ANSI C37.90.2 1995 was at > 35V/M (no modulation) because that was the intensity of a 5W portable radio > 6" from a product. This is supposed to represent the exposure due to work > crews as they test out control circuits etc. > Recently that standard was changed to be more in line with IEC61000-4-3 > methods by shifting to 20V/M with the 80% 1Khz AM modulation. > > With the growth of the cell phone market I am surprised that the 3V/m limit > has held. > I understand that cell phone field strengths are greater than 3V/M but that > is a near field measurement. > I know there have been some changes recently - perhaps others can speak to > that. > > Chris Wells > > > ----- Original Message ----- > From: "Gordon,Ian" <[email protected]> > To: "'IEEE EMC-PSTC GROUP'" <[email protected]> > Sent: Thursday, October 14, 2004 3:30 AM > Subject: Why 3 and 10V/m? > > >> All >> Does anyone know why 3 and 10V/m were chosen for radiated immunity > testing? >> Obviously these are merely the minima to be used, but there must have been >> some logic behind the values? >> If you have information on the logic behind the levels chosen for other >> tests then that would also be appreciated. >> >> Ian Gordon >> >> > > ---------------------------------------------------------------- > 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 [email protected] > > Instructions: http://listserv.ieee.org/listserv/request/user-guide.html > > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Ron Pickard: [email protected] > Scott Douglas [email protected] > > For policy questions, send mail to: > > Richard Nute: [email protected] > Jim Bacher: [email protected] > > 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 [email protected] Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [email protected] Scott Douglas [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
