That is CISPR. ANSI C63.4 does not call for setting the antenna to an 80 MHz resonant length below 80 MHz. That would result in a difference in readings between the two approaches.
Ghery _____ From: Bob Richards [mailto:b...@toprudder.com] Sent: Monday, August 29, 2005 7:10 AM To: Pettit, Ghery; emc-p...@ieee.org Subject: RE: Use of Dipole Antenna's For FCC-A Emissions Testing I may be thinking of CISPR 16, but I know there is a standard that says a tuned dipole, if used vertical, must remain tuned to 80 MHz or so for measurements down to 30 MHz. To properly do this, however, requires calibration factors acquired in that mode as well. Bob Richards, NCT. "Pettit, Ghery" <ghery.pet...@intel.com> wrote: Jeff, ANSI C63.4 still lists the tuned dipole antenna as the preferred antenna for measurements from 30 MHz to 1000 MHz. Vertically polarized you must keep the antenna at least .25 meters above the ground plane, so, yes, you cannot get the center of the antenna 1 meter off the ground plane. Perfectly legal. Just as it was when we did this (not very often, as I recall) at Tandem in the “good old days”. Ghery S. Pettit _____ From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of jeff collins Sent: Friday, August 26, 2005 5:47 PM To: emc-p...@ieee.org Subject: Use of Dipole Antenna's For FCC-A Emissions Testing Hi Group, It's been quite a while since I've done this so I figure I would ping it off the group for a consensus. Back in the old days, you could use a Dipole antenna to take radiated emission measurements for frequencies that were either failing or were close to the limit. Is that still legal for FCC-A radiated emissions testing? For background info, by tuning the dipole antenna to the exact frequency, you were able to obtain a more accurate reading than using a broadband antenna. Sometimes you would gain a few dB, sometimes you would lose a few dB. One thing I remember about this that was flakey, was if you did this for a low end frequency such as 30 Mhz in vertical polarity. At that frequency, the elements on the dipole antenna seem to be about a mile long. There was no way to take a vertical reading at that frequency at a height of 1 meter without breaking the antenna element. You therefore had to raise the antenna above 2+ meters to take the reading. In horizontal polarity this was not an issue. All comments appreciated............. Thanks, Jeff Collins ---------------------------------------------------------------- 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
