Allen, I would like to clarify one point. I use a biconilog in the chamber. All chamber work is "rough" or ballpark.
I use a biconical and a log periodic on the OATS. There are a few articles around that identify repeatability issues with a biconilog. However, for pre-compliance biconilog is adequate as long as you know the antenna's and chamber's limitations. Don > ---------- > From: > umbdenst...@sensormatic.com[SMTP:umbdenst...@sensormatic.com] > Reply To: umbdenst...@sensormatic.com > Sent: Wednesday, November 15, 2000 12:08 PM > To: emc-p...@ieee.org; allen_tu...@pairgain.com > Subject: RE: Which Antenna? > > > Allen, > > We have a similar chamber with similar issues. We use the immunity > chamber > as a precompliance emissions chamber also. It's a lot of work to remove > the > tiles from the floor so we left them in place for precompliance emissions > investigations. We use a biconilog antenna for both emissions and > immunity. > We have found that our "correlation factor" to our OATS is roughly +/- 8 > dB. This works for us as the chamber eliminates the radio and TV ambients > and we can see the entire profile at a glance. We now do 90% of our > emissions mitigation in the chamber and then final compliance measurements > at the OATS. > > Hope this insight helps. > > Don Umbdenstock > Sensormatic > > > ---------- > > From: Tudor, Allen[SMTP:allen_tu...@pairgain.com] > > Reply To: Tudor, Allen > > Sent: Wednesday, November 15, 2000 11:36 AM > > To: emc-p...@ieee.org > > Subject: Which Antenna? > > > > > > Greetings, > > > > I am having a fully anechoic pre-compliance test chamber built. By > fully > > anechoic, I mean ferrite tiles will be installed on the floor as well as > > the > > walls and ceiling. The inner dimensions of the chamber will be 24 feet > > long > > by 14 feet wide by 13 feet high. The chamber will be used for radiated > > emissions as well as radiated immunity. Radiated emissions testing will > > be > > from 30MHz to 1GHz. > > > > I am looking at a biconilog antenna that can be used for emissions and > > immunity testing. However; for emissions measurements, the salesman > > recommends that I use separate biconical and log-periodic antennas. He > > says > > that if I use the biconilog antenna for emissions measurements, there > will > > be some coupling to the ground plane when the antenna is in the vertical > > position. However, this chamber will have ferrite on the floor, so I > > don't > > know if that is a valid argument. > > > > Aside from the expense of two additional antennas, I have two > conflicting > > concerns. > > 1. I would rather not have to work with more than one antenna if I don't > > have to due to down time and possible damage to an antenna. > > 2. On the flip side, I want to make sure that I have repeatable results, > > especially at the low end of the spectrum. > > > > Any advice would be greatly appreciated. > > > > ------------------------------------------- > > This message is from the IEEE EMC Society Product Safety > > Technical Committee emc-pstc discussion list. > > > > To cancel your subscription, send mail to: > > majord...@ieee.org > > with the single line: > > unsubscribe emc-pstc > > > > For help, send mail to the list administrators: > > Jim Bacher: jim_bac...@mail.monarch.com > > Michael Garretson: pstc_ad...@garretson.org > > > > For policy questions, send mail to: > > Richard Nute: ri...@ieee.org > > > > > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Jim Bacher: jim_bac...@mail.monarch.com > Michael Garretson: pstc_ad...@garretson.org > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > > ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson: pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org