I fully agree with Ken. I have many times used house-made "sniffer" probes to locate sources (and also coupling paths and/or antennas) of radiated emissions. They helped me identify and fix a number of compliance issues by pointing to the critical elements. That is the real plus of these tools. On the other end, there is no point trying to correlate near and far-field readings.
Regards, Paolo -----Original Message----- From: Ken Javor [mailto:[email protected]] Sent: Friday, November 22, 2002 12:24 AM To: Jim Bacher; Emc-Pstc (E-mail) Cc: '[email protected]' Subject: Re: EMC E&H close field probes / Mindcruiser My opinion only, curious to see what others say. The relationship between what is measured very close to a source and what is measured at three or ten meters depends very strongly on the efficiency of the radiating element. For example, if a chip by itself were radiating intensely close-in, you would get a very different 3 or 10 m signal than if the chip were connected to a long path on a PCB, and it would radiate still more if that path had a discontinuity in the ground plane beneath it (assuming a high enough frequency) and ground bounce then drove an externally connected cable. So my opinion, for what it's worth, is that trying to correlate measured amplitudes close-in with 3 or 10 m signals is not practical in the general case of troubleshooting a test item. The probe is useful for locating the source of an emission. ---------- >From: Jim Bacher <[email protected]> >To: "Emc-Pstc (E-mail)" <[email protected]> >Cc: "'[email protected]'" <[email protected]> >Subject: FW: EMC E&H close field probes / Mindcruiser >Date: Thu, Nov 21, 2002, 3:46 PM > > > Forwarding for Thomas Krzesaj, please copy Thomas when you respond. > > ------------------------------ > EMC E&H close field probes Message ID: 538546 > > Hi, > > I would like to get more informations about close field probes and the > measurement methods. > What close field value can we consider as critical ? > How to interpret the result from the probe ? > We actually bought Agilent 11941A & 11940a probes and FischerCC E&H close > field probes. > > > My idea is to get an EMC-scanner like the DetectusAB one > (http://www.detectus.se/) to get more repeatibility. Can I get some advices? > > Thanks, > Thomas Krzesaj > > Genius Instituto de Tecnología > Av. Açaí, 875 Bloco E > 69075-904 Distrito Industrial > Manaus - Amazonas > Brasil > > Tel: +55 92 614-6578 / Fax: +55 92 613-3144 > mailto:[email protected] > http://www.thomask.fr.st > http://www.genius.org.br > Posted on Nov 20,2002 at 07:15am > > > > > > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: [email protected] > Dave Heald: [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://ieeepstc.mindcruiser.com/ > Click on "browse" and then "emc-pstc mailing list" > ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [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://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [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://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
