I hadn't thought about it before, but the issue of a) a spec which allows flexibility in antenna-EUT separation, and b) the variable radiation source on a logperiodic makes me think that a track for the antenna with automatic positioning as a function of frequency might be a real good idea, especially for the poor souls who have to meet 1000-4-3 at the 10 V/m level at 26 MHz. I don't think this idea would be difficult or expensive to implement. When ANSI 63.4 started requiring high gain antennas to be boresighted on the EUT all throughout a height search, that was mechanically implemented by mast manufacturers, and I know that several years ago Electrometrics built a mechanical system to tune half-wavelength dipoles.
---------- >From: [email protected] >To: Kevin Hight <[email protected]> >Cc: "Colgan, Chris" <[email protected]>, "'Emc-Pstc' (E-mail)" <[email protected]> >Subject: RE: IEC 61000-4-3 >Date: Fri, Apr 6, 2001, 3:40 PM > > > > Kevin, > > You are _not_ violating the standard when you move one meter closer than > three meters. The _minimum_ distance is defined in the standard as one > meter from the tip of a log-periodic array or the center of a dipole > (biconical or otherwise) to the calibrating plane of the EUT face. Of > course it is essentially impossible to meet the field uniformity > specification with the antenna that close, that's why there is a three > meter recommendation. > > This does bring up an unfortunate problem. Log-periodic array gain is a > function of the taper ratio. The slower the taper (and longer the antenna > for a given frequency range) the more gain you get. This would be > wonderful for those with smaller amplifiers, but it complicates the > situation by moving the effective radiation point of the antenna over a > larger range which, in turn, makes it harder to maintain field strength at > the EUT plane as the frequency decreases. It's a double whammy since your > moving away with a lowering antenna factor. > > Win some lose some (or sometimes just lose some)..... > > Regards, > > Brent DeWitt > Datex-Ohmeda > Louisville, CO > > > > > > > > Kevin Hight <[email protected]>@ieee.org on 04/06/2001 09:04:26 AM > > Please respond to Kevin Hight <[email protected]> > > Sent by: [email protected] > > > To: "Colgan, Chris" <[email protected]>, "'Emc-Pstc' > (E-mail)" <[email protected]> > cc: > > Subject: RE: IEC 61000-4-3 > > > > Chris, > > Allow me to stir the pot a little. > > 1) The antenna is to be 3-meters from the calibrated field. > 2) The antenna may be as long a 1-meter, front-to-back. > 3) The worst performing section of the antenna is the furthest section > away. > > If you move your antenna 1-meter closer, such that the back of the antenna > is 3-meters away, are you violating the standard? > If you move your antenna 1-meter back, such that the front of the antenna > is > 3-meters away, your are adding significant cost to your test setup due to > the additional power requirement. > Is a middle ground the most acceptable, 2.5-meters from the front of the > antenna and 3.5-meters from the back of the antenna, both from a > manufacturers cost and from the standards requirements. > > > Regards, > ____________________________________ > Kevin J. Hight - Principal Compliance Engineer > Colorado MEDtech, Inc. > 6175 Longbow Drive, Boulder, Colorado 80301 > Phone: (303) 530-8288 x-3111 Fax: (303) 581-1003 > Email: [email protected] http://www.cmed.com > > "Man's mind once stretched by a new idea, never regains its original > dimension." > -- Oliver Wendell Holmes > > >> -----Original Message----- >> From: Colgan, Chris [SMTP:[email protected]] >> Sent: Friday, April 06, 2001 2:34 AM >> To: 'Emc-Pstc' (E-mail) >> Subject: RE: IEC 61000-4-3 >> >> >> The calibrated uniform field is a 1.5m square vertical plane 0.8m above >> your >> ground plane and 3m from your antenna, usually the tip (the size of the >> vertical plane and the antenna distance can be smaller but that's not the >> issue here). The EUT is placed so that the panel you are testing is >> illuminated by the vertical field ie the part of the EUT nearest to the >> antenna should always be 3m away. I know this sounds rude and I don't >> mean >> it to be but if you weren't sure that the uniform field was a vertical >> plane, how did you calibrate it? >> >> Regards >> >> Chris Colgan >> Compliance Engineer >> TAG McLaren Audio Ltd >> The Summit, Latham Road >> Huntingdon, Cambs, PE29 6ZU >> *Tel: +44 (0)1480 415 627 >> *Fax: +44 (0)1480 52159 >> * Mailto:[email protected] >> * http://www.tagmclarenaudio.com >> >> >> > -----Original Message----- >> > From: [email protected] >> [SMTP:[email protected]] >> > Sent: 05 April 2001 23:24 >> > To: [email protected] >> > Subject: IEC 61000-4-3 >> > >> > >> > Collogues, >> > >> > In this specification, is it stated anywhere if the unity field is a >> > volume ( 1 cubic meter) or is it a plane location (the calibration >> plane)? >> > >> > I'm having questions raised about rotating the EUT (in 90 degree >> > increments) >> > (which now has us over testing the EUT because it is closer to the >> antenna >> > by 0.3m at the 90 degree point) or under testing when tested at 270 >> > degrees? >> > I thought I had read somewhere that the unity field was the 1 cubic >> meter >> > box at the (80cm) table top centered and aligned with the calibration >> > plane? >> > >> > > Michael Sundstrom >> > > Product Test Technician EMC >> > > Nokia Mobile Phones, Dallas PCC >> > > >> > > * Email [email protected] >> > > % Desk (972) 374-1462 >> > > *Mobile (817) 917-5021 >> > > * Fax (972) 374-0901 >> > amateur call: KB5UKT >> > >> > >> > ------------------------------------------- >> > 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: >> > Michael Garretson: [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://www.rcic.com/ click on "Virtual Conference Hall," >> >> >> ************************************************************** >> Please visit us at www.tagmclarenaudio.com >> ************************************************************** >> >> The contents of this E-mail are confidential and for the exclusive >> use of the intended recipient. If you receive this E-mail in error, >> please delete it from your system immediately and notify us either >> by E-mail, telephone or fax. You should not copy, forward or >> otherwise disclose the content of the E-mail. >> >> TAG McLaren Audio Ltd >> The Summit, 11 Latham Road >> Huntingdon, Cambs, PE29 6ZU >> Telephone : 01480 415600 (+44 1480 415600) >> Facsimile : 01480 52159 (+44 1480 52159) >> >> ************************************************************** >> Please visit us at www.tagmclarenaudio.com >> ************************************************************** >> >> ------------------------------------------- >> 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: >> Michael Garretson: [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://www.rcic.com/ click on "Virtual Conference Hall," > > ------------------------------------------- > 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: > Michael Garretson: [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://www.rcic.com/ click on "Virtual Conference Hall," > > > > > > ------------------------------------------- > 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: > Michael Garretson: [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://www.rcic.com/ click on "Virtual Conference Hall," > ------------------------------------------- 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: Michael Garretson: [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://www.rcic.com/ click on "Virtual Conference Hall,"
