Patrick,
In my company, we have a 10 meter semi-anechoic chamber (lined with cones).
However, sometimes I also need to use an outside EMC test facility. I prefer a
chamber instead of an OATS, because I do only pre-scans, and it is a lot faster
in a chamber. For the first couple of years, I was using a 3 meter fully
anechoic chamber lined with ferrite tiles. This lab uses a BiLog antenna at a
fixed height (it is 1.5 or 2 meters), and applies a correction factor to account
for the reflections that are present in an OATS or a semi-anechoic chamber. I
always had problem co-relating the data between our 10 meter chamber and this 3
meter chamber. Now I use another EMC test facility with a 10 meter chamber,
similar to the one at our company.
The ferrite tiles generally work well to the frequencies of 500 MHz and then
their absorption drops down. Also, keeping antenna at a fixed height does not
provide accurate data for horizontal polarization, where one sees more emissions
at higher antenna heights. Still, a chamber is great for pre-scans and
trouble-shooting and saves you a lot of time. Only once in a while you need to
verify your data at an OATS, or a 10 meter chamber.
Regards, Ravinder
PCB Development and Design Department
Email: ajm...@us.ibm.com
***************************************************************************
Always do right. This will gratify some people and astonish the rest. ....
Mark Twain
"Patrick, Al" <al.patr...@sciatl.com> on 08/19/99 12:28:38 PM
Please respond to "Patrick, Al" <al.patr...@sciatl.com>
To: emc-p...@ieee.org
cc: "Patrick, Al" <al.patr...@sciatl.com>, "'alpatr...@op9.com'"
<alpatr...@op9.com>
Subject: 3-Meter Chamber for Emission Pre-Scanning
To all members of this distinguished group. I now come to you not to make
commitment but to ask your for help.
My situation is this; I had an OATS site to which I wanted to add a 3 Meter
chamber (ETS Model 20) for Immunity test per the EU requirements.
I started this quest in 1997 and have succeeded with the installation this
month.
Now my problem, along the way my company moved into a new campus (Great!),
But now the CEO does not want an ugly OATS around his new campus. Now just
before approving the new 3 Meter chamber, which took two years to get
thirteen signatures, he says "You can do your scanning in this chamber,
Right!" and looks at me just before he signs it.
Now my eyes roll back in my head and I say (the only thing which will save
this project) "Yes Sir"
Assumptions: The chamber will only be used for pre-scans and diagnostics.
I already know that you can't correlate a 3 Meter chamber to a 10 Meter
OATS, but I have to try at least try until I can build a 10 OATS somewhere.
I would like to hear from members who have used, or tried to use a 3 meter
(10x10x22 FT. chamber lined with ferrite tile) for emission scans.
I have already found that 1 Meter is about the best distant to scan with out
to many reflections but it's easy to miss an emission too.
I'm "all ears" as they say.
Thank you,
Al Patrick, EMC Lab Manager
Scientific-Atlanta Inc.
al.patr...@sciatl.com
Title: 3-Meter Chamber for Emission Pre-Scanning
To all members of this distinguished group. I now come to you not to make commitment but to ask your for help.
My situation is this; I had an OATS site to which I wanted to add a 3 Meter chamber (ETS Model 20) for Immunity test per the EU requirements.
I started this quest in 1997 and have succeeded with the installation this month.
Now my problem, along the way my company moved into a new campus (Great!), But now the CEO does not want an ugly OATS around his new campus. Now just before approving the new 3 Meter chamber, which took two years to get thirteen signatures, he says "You can do your scanning in this chamber, Right!" and looks at me just before he signs it.
Now my eyes roll back in my head and I say (the only thing which will save this project) "Yes Sir"
Assumptions: The chamber will only be used for pre-scans and diagnostics.
I already know that you can't correlate a 3 Meter chamber to a 10 Meter OATS, but I have to try at least try until I can build a 10 OATS somewhere.
I would like to hear from members who have used, or tried to use a 3 meter (10x10x22 FT. chamber lined with ferrite tile) for emission scans.
I have already found that 1 Meter is about the best distant to scan with out to many reflections but it's easy to miss an emission too.
I'm "all ears" as they say.
Thank you,
Al Patrick, EMC Lab Manager
Scientific-Atlanta Inc.
al.patr...@sciatl.com
