The closest thing I have heard about was a claim by one of Chris Kendall's
engineers that he could get correlatible data between a small ferrite
shielded room and an OATS site. It did however, have to develop and antenna
height factor, if you will. The room is roughly 10 by 12 by 20 feet (for
Europe that's about as useful as furlongs per fortnight but anyway...) The
biggest problem was the inability to raise the antenna. With some
mathematically trickery they were able to apply this factor and claimed to
be within a dB of the actual OATs measurement.
The article didn't describe the complexity of the equipment under test so
there could be a whole raft of problems there, and you would have to be of
the short that believes that the FCC 3 meter testing is valid and many do
not.
The good news is that the cost of such a chamber starts to fall more in-line
with what people can afford and even more important could be put in many
buildings that already exist in every city. Now at least EMC vendors could
move near us, rather than we having to travel to them, plus the other
benefits that such a room can bring to the table.
The bad news is that they have a long way to go in convincing the
appropriate people that it really works, and they still had some problems at
th 30 to 60 MHz region and were looking for some acceptance of a fudge
factor in this range.
Before the scoffing begins at my useless optimism, I might point out that
not long ago the same problems existed for the large chambers, but many of
the big kids are quite happily qualifying stuff in those.
It is a long shot but I would certainly wish them success if they
can do it, and any start is a good start.
I haven't been in touch with them lately to know of their progress.
Gary
-----Original Message-----
From: Roman, Dan [SMTP:[email protected]]
Sent: Friday, June 18, 1999 12:29 PM
To: '[email protected]'
Subject: RE: NEAR/ FAR FIELD CORRELATION ISSUES
I also have been following this thread with interest, but even more
practical and technically less challenging alternate methods of
testing take
too long for acceptance in my opinion. Forget near-field
measurements with
probes, I'd like to see quicker movement on acceptance of standards
like
EN50147-3 for fully anechoic compact chambers. I'm not going to get
greedy
and look for (or expect) near field or cable clamp measurement
acceptance in
the near future.
Since I mentioned it, does anyone know if there is movement or
progress in
the area of standards tailored specifically for compact chambers
like
EN50147-3?
--
Dan Roman, Compliance Engineer * mailto:[email protected]
*Voice: +1 (973) 993-3000 ext. 6485 Fax: +1 (973) 993-8466
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