Near field H-field measurement.
Dear experts, I am measuring the fundamental and spurious emissions from an EUT ( with interanl loop antenna) of fundamental frequencies of about 50kHz to 200kHz. The measuring range of spurious emission is up to 1GHz. The limits are according to a local standard from a local regulatory body. The emission limits for both fundamental and spurious emissions are quoted in electric field ( dBuV/m) and magnetic field (dBuA/m), means the emissions from the EUT must not exceed the limits of both E field AND H-field. The spectrum analyzer display (dBuV/m) because it already included the transducer factor ( magnetic field antenna factor:-55dB/m and the cable loss). I am using EMCO 6502 loop antenna for the radiated emission measurement at 10 measuring distance. Since the limits are quoted by the regulatory body are at 30 and 300 meters distance, so I use extrapolation factor (value of 3) i.e. 20 log (300/10)^3 to determine the corresponding limit at 10 meters from a 300 meters limit which equals to 88.3dB mark up for the H-field. My questions are : 1. From theory, if both Tx and Rx antennas are loops antenna, under near field conditions, H-fields is predominant, so the H-field is inversely proportional to D^3, so I use the extrapolation factor 3. For H-field measurement , I just use the reading from the spectrum analyzer plus the cable loss and magnetic antenna factor (-5dB), and use this calculated value to compare with the extrapolation value. please correct me if I am wrong. ( I know there is another approach of extrapolate the measured value and compare with the limits). Please correct me the method and extrapolation factor if I am wrong. 2. Since the requirement of the limits are in both H-field and E-field. Which extrapolation factor (2 or 3) should be used to determine the limit from i.e. 300 meters to 10 meters? The reason of supporting if use 2 is because under near field coditions, the E-field is inversely proportional to D^2. But now both Tx and Rx antennas are loop antennas, so finally I use 3 to extrapolate the limit of E-field ( i.e. from 300 to 10 meters) and compare with the spectrum analyzer reading, please comment and/or correct me if I am wrong. Thanks advance for your any comment or opinion. Regards, Derek Leung. 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/listserv/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: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Radiated emission : Plasma TV vs. LCD TV
All things being equal (and of course, they never are), I would expect that a plasma display would be noisier. The scan rates of the two displays are equal, but the voltages swings are larger for a plasma display. Plus the power is much higher for a plasma display - just stand near one and you will feel the heat radiated by the display. Higher power means higher current, means (all things being equal) higher emissions. Don Borowski Schweitzer Engineering Labs Pullman, WA, USA "Amund Westin" wrote on 06/21/2005 01:28:51 PM: > In general, is it possible to say which one that has the lowest radiation? > > Cheers! > > #Amund Westin > Oslo / Norway 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/listserv/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 Cantwellmcantw...@ieee.org For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Radiated emission : Plasma TV vs. LCD TV
In general, is it possible to say which one that has the lowest radiation? Cheers! #Amund Westin Oslo / Norway 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/listserv/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 Cantwellmcantw...@ieee.org For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Status of EN 55022
melli...@tycoint.com wrote (in <2141C5F52FD2CA4182AF6927090263B90F61B247@flbocexu04>) about 'Status of EN 55022', on Tue, 21 Jun 2005: >I know that over the last year there has been a lot of talk about the >[quickly] upcoming EN 55022 requirements on the OJ. > >There had been some discussion regarding updated versions being >circulated that would resolve some of the differences between CISPR 22 >and EN 55022. > >Does anyone know of the status? It will be discussed again at a CENELEC meeting on Thursday and Friday of this week. Solutions are being proposed and it will be necessary to make a final decision at this meeting, if at all possible. It appears likely that CENELEC Technical Board will have to be asked to take some action to help resolve the problem, and that may result in a further delay. > >My current understanding is that since I use EN 301 489-1 and EN >61000-6-3 for some of our products, that the requirements require the >latest revision of the standard on the OJ, which would be EN 55022 1998. > >On August 1st, I will have to apply A1 which require the ferrite tubes >on cables. > >In December, A2 goes into effect. I believe the multi-functional >equipment requirements / definition is the primary change here. > >For equipment that was tested before August 1st, 2005 on OATS or at >test labs not using the ferrite tubes, is it required [or suggested] >that the equipment be retested now using the ferrite tubes to >demonstrate compliance to A1? I will take a copy of your message to the meeting to highlight the sort of questions that need urgent answers. The matter of UNDATED references to EN 55022 in other standards is an issue that certainly needs to be checked out. -- Regards, John Woodgate, OOO - Own Opinions Only. Deadlines are 90% of deadliness. http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk 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/listserv/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 Cantwellmcantw...@ieee.org For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Near field H-field measurement.
Derek, The FCC specifies using a loop antenna for measuring field strength below 30 MHz. Extrapolation can be used if the field strength is measured at two distances and the factor calculated (it will be close to 1/R^3), otherwise the default of 40 dB/decade (1/R^2) must be used. We normally use 30 m and 10 m for the two distances. We have taken measurements at 300 m, 30 m, and 10 m and found the extrapolation factor to be consistent. At these frequencies, there is negligible difference with or without a ground plane. Regards, Frank de Vall Sr. Engineering Manager - Compliance Assa Abloy ITG and HID Corporation Y W Leung To Sent by: emc-p...@ieee.org owner-emc-pstc@ie cc ee.org Subject Near field H-field measurement. 06/20/2005 11:56 PM Dear experts, I am measuring the fundamental and spurious emissions from an EUT ( with interanl loop antenna) of fundamental frequencies of about 50kHz to 200kHz. The measuring range of spurious emission is up to 1GHz. The limits are according to a local standard from a local regulatory body. The emission limits for both fundamental and spurious emissions are quoted in electric field ( dBuV/m) and magnetic field (dBuA/m), means the emissions from the EUT must not exceed the limits of both E field AND H-field. The spectrum analyzer display (dBuV/m) because it already included the transducer factor ( magnetic field antenna factor:-55dB/m and the cable loss). I am using EMCO 6502 loop antenna for the radiated emission measurement at 10 measuring distance. Since the limits are quoted by the regulatory body are at 30 and 300 meters distance, so I use extrapolation factor (value of 3) i.e. 20 log (300/10)^3 to determine the corresponding limit at 10 meters from a 300 meters limit which equals to 88.3dB mark up for the H-field. My questions are : 1. From theory, if both Tx and Rx antennas are loops antenna, under near field conditions, H-fields is predominant, so the H-field is inversely proportional to D^3, so I use the extrapolation factor 3. For H-field measurement , I just use the reading from the spectrum analyzer plus the cable loss and magnetic antenna factor (-5dB), and use this calculated value to compare with the extrapolation value. please correct me if I am wrong. ( I know there is another approach of extrapolate the measured value and compare with the limits). Please correct me the method and extrapolation factor if I am wrong. 2. Since the requirement of the limits are in both H-field and E-field. Which extrapolation factor (2 or 3) should be used to determine the limit >from i.e. 300 meters to 10 meters? The reason of supporting if use 2 is because under near field coditions, the E-field is inversely proportional to D^2. But now both Tx and Rx antennas are loop antennas, so finally I use 3 to extrapolate the limit of E-field ( i.e. from 300 to 10 meters) and compare with the spectrum analyzer reading, please comment and/or correct me if I am wrong. Thanks advance for your any comment or opinion. Regards, Derek Leung. 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/listserv/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: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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/listserv/request/user-guide.html List rules: http://w
RE: Near field H-field measurement.
Derek and Robert, The fields from an electric dipole drop off as: Magnetic: 1/r^2 and 1/r Electric: 1/E^3, 1/E^2, and 1/E For a magnetic dipole (loop): Magnetic: 1/r^3, 1/r^2 and 1/r Electric: 1/E^2, and 1/E This link provides the formulas that will allow to to calculate the field strength versus distance. http://www.conformity.com/0102reflections.html I have correlated these formulas to NEC-2 to confirm that NEC-2 can be used to find the H or E field strength at various distances. Dave Cuthbert Micron Technology From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org] On Behalf Of Robert A. Macy Sent: Tuesday, June 21, 2005 8:58 AM To: Y W Leung Cc: emc-p...@ieee.org Subject: Re: Near field H-field measurement. Near field?! You're way inside near field below 200KHz. At those fundamental frequencies, you are correct. Magnetic fields drop at the rate of inverse cube from a dipole. You didn't say the size of the EUT. However, if it is smaller than 1/5 the distance to the antenna, you can correctly assume the "nonradiating" magnetic field is dropping at inverse cube. I'm reluctant to rely on any accuracy using a loop to measure E-Field at that low a frequency. Should use a field probe. The E Field should drop off as the inverse square function. In the range of 50-200KHz, measure E-Field and H-Field at two distances and you should see those ratios. - Robert - On Tue, 21 Jun 2005 13:56:25 +0800 (CST) Y W Leung wrote: > Dear experts, > > I am measuring the fundamental and spurious emissions > from an EUT ( with interanl loop antenna) of fundamental > frequencies of about 50kHz to 200kHz. The measuring range > of spurious emission is up to 1GHz. > > The limits are according to a local standard from a local > regulatory body. > The emission limits for both fundamental and spurious > emissions are quoted in electric field ( dBuV/m) and > magnetic field (dBuA/m), means the emissions from the EUT > must not exceed the limits of both E field AND H-field. > The spectrum analyzer display (dBuV/m) because it already > included the transducer factor ( magnetic field antenna > factor:-55dB/m and the cable loss). > > I am using EMCO 6502 loop antenna for the radiated > emission measurement at 10 measuring distance. Since the > limits are quoted by the regulatory body are at 30 and > 300 meters distance, so I use extrapolation factor (value > of 3) i.e. 20 log (300/10)^3 to determine the > corresponding limit at 10 meters from a 300 meters limit > which equals to 88.3dB mark up for the H-field. > > My questions are : > > 1. From theory, if both Tx and Rx antennas are loops > antenna, under near field conditions, H-fields is > predominant, so the H-field is inversely proportional to > D^3, so I use the extrapolation factor 3. For H-field > measurement , I just use the reading from the spectrum > analyzer plus the cable loss and magnetic antenna factor > (-5dB), and use this calculated value to compare with the > extrapolation value. please correct me if I am wrong. ( I > know there is another approach of extrapolate the > measured value and compare with the limits). Please > correct me the method and extrapolation factor if I am > wrong. > > > 2. Since the requirement of the limits are in both > H-field and E-field. Which extrapolation factor (2 or 3) > should be used to determine the limit from i.e. 300 > meters to 10 meters? The reason of supporting if use 2 is > because under near field coditions, the E-field is > inversely proportional to D^2. But now both Tx and Rx > antennas are loop antennas, so finally I use 3 to > extrapolate the limit of E-field ( i.e. from 300 to 10 > meters) and compare with the spectrum analyzer reading, > please comment and/or correct me if I am wrong. > > Thanks advance for your any comment or opinion. > > Regards, > > Derek Leung. > > > > > > > > > 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/listserv/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 Cantwellmcantw...@ieee.org > > For policy questions, send mail to: > > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > 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/listserv/request/user-guide.html List rules: ht
Re: Near field H-field measurement.
Forgot! E Fields from a true dipole do drop off at the inverse cube rate also, It's just that the fields almost always get referenced to a ground or ground plane which makes them drop off for all practical purposes at the rate of the inverse square. - Robert - > From: Y W Leung > Date: Tue, 21 Jun 2005 13:56:25 +0800 (CST) > To: emc-p...@ieee.org > Subject: Near field H-field measurement. > > Dear experts, > > I am measuring the fundamental and spurious emissions > from an EUT ( with > interanl loop antenna) of fundamental frequencies of > about 50kHz to 200kHz. > The measuring range of spurious emission is up to 1GHz. > > The limits are according to a local standard from a local > regulatory body. > The emission limits for both fundamental and spurious > emissions are quoted > in electric field ( dBuV/m) and magnetic field (dBuA/m), > means the emissions > from the EUT must not exceed the limits of both E field > AND H-field. The > spectrum analyzer display (dBuV/m) because it already > included the > transducer factor ( magnetic field antenna factor:-55dB/m > and the cable > loss). > > I am using EMCO 6502 loop antenna for the radiated > emission measurement at > 10 measuring distance. Since the limits are quoted by the > regulatory body > are at 30 and 300 meters distance, so I use extrapolation > factor (value of > 3) i.e. 20 log (300/10)^3 to determine the corresponding > limit at 10 meters > from a 300 meters limit which equals to 88.3dB mark up > for the H-field. > > My questions are : > > 1. From theory, if both Tx and Rx antennas are loops > antenna, under near > field conditions, H-fields is predominant, so the H-field > is inversely > proportional to D^3, so I use the extrapolation factor 3. > For H-field > measurement , I just use the reading from the spectrum > analyzer plus the > cable loss and magnetic antenna factor (-5dB), and use > this calculated value > to compare with the extrapolation value. please correct > me if I am wrong. ( > I know there is another approach of extrapolate the > measured value and > compare with the limits). Please correct me the method > and extrapolation > factor if I am wrong. > > > 2. Since the requirement of the limits are in both > H-field and E-field. > Which extrapolation factor (2 or 3) should be used to > determine the limit > from i.e. 300 meters to 10 meters? The reason of > supporting if use 2 is > because under near field coditions, the E-field is > inversely proportional to > D^2. But now both Tx and Rx antennas are loop antennas, > so finally I use 3 > to extrapolate the limit of E-field ( i.e. from 300 to 10 > meters) and > compare with the spectrum analyzer reading, please > comment and/or correct me > if I am wrong. > > Thanks advance for your any comment or opinion. > > Regards, > > Derek Leung. > > 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/listserv/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 Cantwellmcantw...@ieee.org For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Near field H-field measurement.
Derek, are your magnetic field measurements only in the range of 50 to 200 kHz? Or, do you intend to measure to 1 GHz? If the former, you may need to modify your 300 to 10 meter scaling for specific frequencies between 50 and 200 kHz. I can find you the formula for this. If the latter, you definitely need to modify the scaling formula. Dave Cuthbert Micron Technology _ From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org] On Behalf Of Y W Leung Sent: Monday, June 20, 2005 11:56 PM To: emc-p...@ieee.org Subject: Near field H-field measurement. Dear experts, I am measuring the fundamental and spurious emissions from an EUT ( with interanl loop antenna) of fundamental frequencies of about 50kHz to 200kHz. The measuring range of spurious emission is up to 1GHz. The limits are according to a local standard from a local regulatory body. The emission limits for both fundamental and spurious emissions are quoted in electric field ( dBuV/m) and magnetic field (dBuA/m), means the emissions from the EUT must not exceed the limits of both E field AND H-field. The spectrum analyzer display (dBuV/m) because it already included the transducer factor ( magnetic field antenna factor:-55dB/m and the cable loss). I am using EMCO 6502 loop antenna for the radiated emission measurement at 10 measuring distance. Since the limits are quoted by the regulatory body are at 30 and 300 meters distance, so I use extrapolation factor (value of 3) i.e. 20 log (300/10)^3 to determine the corresponding limit at 10 meters from a 300 meters limit which equals to 88.3dB mark up for the H-field. My questions are : 1. From theory, if both Tx and Rx antennas are loops antenna, under near field conditions, H-fields is predominant, so the H-field is inversely proportional to D^3, so I use the extrapolation factor 3. For H-field measurement , I just use the reading from the spectrum analyzer plus the cable loss and magnetic antenna factor (-5dB), and use this calculated value to compare with the extrapolation value. please correct me if I am wrong. ( I know there is another approach of extrapolate the measured value and compare with the limits). Please correct me the method and extrapolation factor if I am wrong. 2. Since the requirement of the limits are in both H-field and E-field. Which extrapolation factor (2 or 3) should be used to determine the limit from i.e. 300 meters to 10 meters? The reason of supporting if use 2 is because under near field coditions, the E-field is inversely proportional to D^2. But now both Tx and Rx antennas are loop antennas, so finally I use 3 to extrapolate the limit of E-field ( i.e. from 300 to 10 meters) and compare with the spectrum analyzer reading, please comment and/or correct me if I am wrong. Thanks advance for your any comment or opinion. Regards, Derek Leung. 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/listserv/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: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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/listserv/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: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Near field H-field measurement.
Mr.. Leung, At low frequencies, you may have undesirable effects from underground pipes / etc... Or your EUT may be significantly large compared to the antenna to influence the measurement. This makes the assumption of 3rd order rolloff uncertain. The FCC guidance is to measure at 2 distances to establish the extrapolation factor that you do have [due to external effects / size of EUT vs measuring distance / etc.] or to use a 40 dB / decade [or inverse square] extrapolation factor. If you are measuring at 10 meters, take another measurement of the fundamental frequencies at 20 meters. If you truly have a 3rd order rolloff of the field then the difference of the H-field readings at 10 meters and 20 meters will be 18 dB different. This corresponds to 20 * [ rolloff factor] dB/ decade. For a factor of 3, you have a 60 dB / decade rolloff of the field. If you do not have a difference of 18 dB, you can calculate what the correct extrapolation factor is. Hope this helps. Best regards, Mac Elliott From: Y W Leung List-Post: emc-pstc@listserv.ieee.org Date: Tue, 21 Jun 2005 13:56:25 +0800 (CST) To: emc-p...@ieee.org Subject: Near field H-field measurement. Dear experts, I am measuring the fundamental and spurious emissions from an EUT ( with interanl loop antenna) of fundamental frequencies of about 50kHz to 200kHz. The measuring range of spurious emission is up to 1GHz. The limits are according to a local standard from a local regulatory body. The emission limits for both fundamental and spurious emissions are quoted in electric field ( dBuV/m) and magnetic field (dBuA/m), means the emissions from the EUT must not exceed the limits of both E field AND H-field. The spectrum analyzer display (dBuV/m) because it already included the transducer factor ( magnetic field antenna factor:-55dB/m and the cable loss). I am using EMCO 6502 loop antenna for the radiated emission measurement at 10 measuring distance. Since the limits are quoted by the regulatory body are at 30 and 300 meters distance, so I use extrapolation factor (value of 3) i.e. 20 log (300/10)^3 to determine the corresponding limit at 10 meters from a 300 meters limit which equals to 88.3dB mark up for the H-field. My questions are : 1. From theory, if both Tx and Rx antennas are loops antenna, under near field conditions, H-fields is predominant, so the H-field is inversely proportional to D^3, so I use the extrapolation factor 3. For H-field measurement , I just use the reading from the spectrum analyzer plus the cable loss and magnetic antenna factor (-5dB), and use this calculated value to compare with the extrapolation value. please correct me if I am wrong. ( I know there is another approach of extrapolate the measured value and compare with the limits). Please correct me the method and extrapolation factor if I am wrong. 2. Since the requirement of the limits are in both H-field and E-field. Which extrapolation factor (2 or 3) should be used to determine the limit from i.e. 300 meters to 10 meters? The reason of supporting if use 2 is because under near field coditions, the E-field is inversely proportional to D^2. But now both Tx and Rx antennas are loop antennas, so finally I use 3 to extrapolate the limit of E-field ( i.e. from 300 to 10 meters) and compare with the spectrum analyzer reading, please comment and/or correct me if I am wrong. Thanks advance for your any comment or opinion. Regards, Derek Leung. 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/listserv/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: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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/listserv/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: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: Near field H-field measurement.
Near field?! You're way inside near field below 200KHz. At those fundamental frequencies, you are correct. Magnetic fields drop at the rate of inverse cube from a dipole. You didn't say the size of the EUT. However, if it is smaller than 1/5 the distance to the antenna, you can correctly assume the "nonradiating" magnetic field is dropping at inverse cube. I'm reluctant to rely on any accuracy using a loop to measure E-Field at that low a frequency. Should use a field probe. The E Field should drop off as the inverse square function. In the range of 50-200KHz, measure E-Field and H-Field at two distances and you should see those ratios. - Robert - On Tue, 21 Jun 2005 13:56:25 +0800 (CST) Y W Leung wrote: > Dear experts, > > I am measuring the fundamental and spurious emissions > from an EUT ( with interanl loop antenna) of fundamental > frequencies of about 50kHz to 200kHz. The measuring range > of spurious emission is up to 1GHz. > > The limits are according to a local standard from a local > regulatory body. > The emission limits for both fundamental and spurious > emissions are quoted in electric field ( dBuV/m) and > magnetic field (dBuA/m), means the emissions from the EUT > must not exceed the limits of both E field AND H-field. > The spectrum analyzer display (dBuV/m) because it already > included the transducer factor ( magnetic field antenna > factor:-55dB/m and the cable loss). > > I am using EMCO 6502 loop antenna for the radiated > emission measurement at 10 measuring distance. Since the > limits are quoted by the regulatory body are at 30 and > 300 meters distance, so I use extrapolation factor (value > of 3) i.e. 20 log (300/10)^3 to determine the > corresponding limit at 10 meters from a 300 meters limit > which equals to 88.3dB mark up for the H-field. > > My questions are : > > 1. From theory, if both Tx and Rx antennas are loops > antenna, under near field conditions, H-fields is > predominant, so the H-field is inversely proportional to > D^3, so I use the extrapolation factor 3. For H-field > measurement , I just use the reading from the spectrum > analyzer plus the cable loss and magnetic antenna factor > (-5dB), and use this calculated value to compare with the > extrapolation value. please correct me if I am wrong. ( I > know there is another approach of extrapolate the > measured value and compare with the limits). Please > correct me the method and extrapolation factor if I am > wrong. > > > 2. Since the requirement of the limits are in both > H-field and E-field. Which extrapolation factor (2 or 3) > should be used to determine the limit from i.e. 300 > meters to 10 meters? The reason of supporting if use 2 is > because under near field coditions, the E-field is > inversely proportional to D^2. But now both Tx and Rx > antennas are loop antennas, so finally I use 3 to > extrapolate the limit of E-field ( i.e. from 300 to 10 > meters) and compare with the spectrum analyzer reading, > please comment and/or correct me if I am wrong. > > Thanks advance for your any comment or opinion. > > Regards, > > Derek Leung. > > > > > > > > > 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/listserv/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 Cantwellmcantw...@ieee.org > > For policy questions, send mail to: > > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > 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/listserv/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 Cantwellmcantw...@ieee.org For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
RE: Near field H-field measurement.
Mr. Leung, Here is an excerpt from the FCC Rules pertaining to measurements below 30 MHz using a loop antenna. "At frequencies below 30 MHz, measurements may be performed at a distance closer than that specified in the regulations; however, an attempt should be made to avoid making measurements in the near field. Pending the development of an appropriate measurement procedure for measurements performed below 30 MHz, when performing measurements at a closer distance than specified, the results shall be extrapolated to the specified distance by either making measurements at a minimum of two distances on at least one radial to determine the proper extrapolation factor or by using the square of an inverse linear distance extrapolation factor (40 dB/decade)." Bill Stumpf D.L.S. Electronics 166 South Carter Street Genoa City WI 53128 bstu...@dlsemc.com phone: 262.279.0210 _ From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org] On Behalf Of Ken Javor Sent: Tuesday, June 21, 2005 9:19 AM To: emc-p...@ieee.org Subject: Re: Near field H-field measurement. A limit specified at 300 meters is outside my experience. I have seen limits at 1 m (military ), and 3, 10, and 30 meters (commercial). I'm not sure how to extrapolate below 30 MHz where you are using the EMCO loop. But above 30 MHz where you are only measuring electric field, the extrapolation is 1/r, that is, electric field rolls off linearly with increasing distance. It does not matter that the sources are magnetic loops - at 30 MHz and up you are so far above the intentional emissions that the radiating source doesn't look like a magnetic loop anymore, it is a fortuitous conductor, and you are in its far field so the impedance of the field is that of free space. From: Y W Leung List-Post: emc-pstc@listserv.ieee.org Date: Tue, 21 Jun 2005 13:56:25 +0800 (CST) To: emc-p...@ieee.org Subject: Near field H-field measurement. Dear experts, I am measuring the fundamental and spurious emissions from an EUT ( with interanl loop antenna) of fundamental frequencies of about 50kHz to 200kHz. The measuring range of spurious emission is up to 1GHz. The limits are according to a local standard from a local regulatory body. The emission limits for both fundamental and spurious emissions are quoted in electric field ( dBuV/m) and magnetic field (dBuA/m), means the emissions from the EUT must not exceed the limits of both E field AND H-field. The spectrum analyzer display (dBuV/m) because it already included the transducer factor ( magnetic field antenna factor:-55dB/m and the cable loss). I am using EMCO 6502 loop antenna for the radiated emission measurement at 10 measuring distance. Since the limits are quoted by the regulatory body are at 30 and 300 meters distance, so I use extrapolation factor (value of 3) i.e. 20 log (300/10)^3 to determine the corresponding limit at 10 meters from a 300 meters limit which equals to 88.3dB mark up for the H-field. My questions are : 1. From theory, if both Tx and Rx antennas are loops antenna, under near field conditions, H-fields is predominant, so the H-field is inversely proportional to D^3, so I use the extrapolation factor 3. For H-field measurement , I just use the reading from the spectrum analyzer plus the cable loss and magnetic antenna factor (-5dB), and use this calculated value to compare with the extrapolation value. please correct me if I am wrong. ( I know there is another approach of extrapolate the measured value and compare with the limits). Please correct me the method and extrapolation factor if I am wrong. 2. Since the requirement of the limits are in both H-field and E-field. Which extrapolation factor (2 or 3) should be used to determine the limit from i.e. 300 meters to 10 meters? The reason of supporting if use 2 is because under near field coditions, the E-field is inversely proportional to D^2. But now both Tx and Rx antennas are loop antennas, so finally I use 3 to extrapolate the limit of E-field ( i.e. from 300 to 10 meters) and compare with the spectrum analyzer reading, please comment and/or correct me if I am wrong. Thanks advance for your any comment or opinion. Regards, Derek Leung. 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/listserv/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: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc -
Re: Near field H-field measurement.
A limit specified at 300 meters is outside my experience. I have seen limits at 1 m (military ), and 3, 10, and 30 meters (commercial). I'm not sure how to extrapolate below 30 MHz where you are using the EMCO loop. But above 30 MHz where you are only measuring electric field, the extrapolation is 1/r, that is, electric field rolls off linearly with increasing distance. It does not matter that the sources are magnetic loops - at 30 MHz and up you are so far above the intentional emissions that the radiating source doesn't look like a magnetic loop anymore, it is a fortuitous conductor, and you are in its far field so the impedance of the field is that of free space. From: Y W Leung List-Post: emc-pstc@listserv.ieee.org Date: Tue, 21 Jun 2005 13:56:25 +0800 (CST) To: emc-p...@ieee.org Subject: Near field H-field measurement. Dear experts, I am measuring the fundamental and spurious emissions from an EUT ( with interanl loop antenna) of fundamental frequencies of about 50kHz to 200kHz. The measuring range of spurious emission is up to 1GHz. The limits are according to a local standard from a local regulatory body. The emission limits for both fundamental and spurious emissions are quoted in electric field ( dBuV/m) and magnetic field (dBuA/m), means the emissions from the EUT must not exceed the limits of both E field AND H-field. The spectrum analyzer display (dBuV/m) because it already included the transducer factor ( magnetic field antenna factor:-55dB/m and the cable loss). I am using EMCO 6502 loop antenna for the radiated emission measurement at 10 measuring distance. Since the limits are quoted by the regulatory body are at 30 and 300 meters distance, so I use extrapolation factor (value of 3) i.e. 20 log (300/10)^3 to determine the corresponding limit at 10 meters from a 300 meters limit which equals to 88.3dB mark up for the H-field. My questions are : 1. From theory, if both Tx and Rx antennas are loops antenna, under near field conditions, H-fields is predominant, so the H-field is inversely proportional to D^3, so I use the extrapolation factor 3. For H-field measurement , I just use the reading from the spectrum analyzer plus the cable loss and magnetic antenna factor (-5dB), and use this calculated value to compare with the extrapolation value. please correct me if I am wrong. ( I know there is another approach of extrapolate the measured value and compare with the limits). Please correct me the method and extrapolation factor if I am wrong. 2. Since the requirement of the limits are in both H-field and E-field. Which extrapolation factor (2 or 3) should be used to determine the limit from i.e. 300 meters to 10 meters? The reason of supporting if use 2 is because under near field coditions, the E-field is inversely proportional to D^2. But now both Tx and Rx antennas are loop antennas, so finally I use 3 to extrapolate the limit of E-field ( i.e. from 300 to 10 meters) and compare with the spectrum analyzer reading, please comment and/or correct me if I am wrong. Thanks advance for your any comment or opinion. Regards, Derek Leung. 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/listserv/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: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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/listserv/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: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Status of EN 55022
I know that over the last year there has been a lot of talk about the [quickly] upcoming EN 55022 requirements on the OJ. There had been some discussion regarding updated versions being circulated that would resolve some of the differences between CISPR 22 and EN 55022. Does anyone know of the status? My current understanding is that since I use EN 301 489-1 and EN 61000-6-3 for some of our products, that the requirements require the latest revision of the standard on the OJ, which would be EN 55022 1998. On August 1st, I will have to apply A1 which require the ferrite tubes on cables. In December, A2 goes into effect. I believe the multi-functional equipment requirements / definition is the primary change here. For equipment that was tested before August 1st, 2005 on OATS or at test labs not using the ferrite tubes, is it required [or suggested] that the equipment be retested now using the ferrite tubes to demonstrate compliance to A1? Feedback? Best Regards, Mac Elliott EMC Engineer Tyco Safety Products / Sensormatic 6600 Congress Avenue Boca Raton, FL 33487 (561)-912-6462 melli...@tycoint.com 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/listserv/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: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Suggestions - Flush Mounted AC Mains
Greetings fellow Group Members, We are preparing to construct a new OATS and I am in the middle of generating my requirements document. I was wondering if any of you have any practical solutions to the flush mounted AC mains receptacles - directly coupled to the horizontal ground plane. Of course, the issue is the rotation of the turntable and the twisting of the cables. I would like to keep the center hole of the turntable open if possible to allow pass-through for connection of cables to remotely located devices [i.e. ANSI C63.4 6.1.2.1]. Also, with regards to EN 55022, there is a statement that AMNs, if used, shall be installed under the ground plane for radiated measurements. Does anyone have any feedback on this practice, especially with regards to equipment with multiple power connections? Best Regards, Mac Elliott EMC Engineer Tyco Safety Products / Sensormatic 6600 Congress Avenue Boca Raton, FL 33487 (561)-912-6462 melli...@tycoint.com 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/listserv/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: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
ethernet radiated emissions- thanks
Dear colleagues; I would like to thank all those who replied to my predicament regarding emissions from an Ethernet port. I have had some first-class advice which will help me solve the problem. Many thanks; Ian McBurney. Allen & Heath Limited. email: ian.mcbur...@allen-heath.com ***LEGAL DISCLAIMER: READ THIS FIRST*** This Email and any files transmitted with it are confidential and intended solely for the use of the individual to whom or the entity to which they are addressed. If you have received this email in error please notify the sender immediately. Please note that any views or opinions presented in this email are those of the author and do not necessarily represent those of Allen & Heath Limited. This email has been checked for the presence of viruses using Sophos AV Scanner. Anti-virus updates are downloaded on a daily basis . The recipient should also check this email and any attachments for the presence of viruses. Allen & Heath Limited accepts no liability for any damage caused by any virus transmitted via this email. *** 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/listserv/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: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
