You should never use an un-lined shielded room for either radiated emissions or
radiated susceptibility tests, even on a preliminary basis. The reflections of
the RF signals off the walls, floor and ceiling cause errors of 20dB or more.
Nulls will hide certain signals and resonances will amplify others randomly and
unpredictably. You can see the strong effect of nulls and resonances by just
slightly moving either the equipment you are testing or the antenna. You will
never get any sort of meaningful test data. Lining the 4 walls and ceiling of
the chamber with ferrite absorbing material is absolutely necessarily if you
want to have any confidence at all in radiated test results.
"Gorodetsky, Vitaly" <[email protected]> on 12/14/2000 03:05:38 PM
Please respond to "Gorodetsky, Vitaly" <[email protected]>
To: "Emc-Pstc (E-mail)" <[email protected]>
cc: (bcc: Jim Hulbert/MSD/US/PBI)
Subject: Shielded Room
Dear Colleagues,
I have been asked to comment on the scope of use/capabilities of shielded
rooms (2-3m x 2m). I would appreciate if you would share your opinion on
the usefulness of Radiated Emissions tests, validity of data, effectiveness
of establishing an emissions baseline information of approved products for
future design changes. Any recommendations for improving the usefulness?
Please do not limit yourself to the above and feel free to expand.
Any comments, advice will be greatly appreciated.
Vitaly Gorodetsky
Compliance Engineer Direct: (818) 678-3840
Canoga Perkins Corp. Main: (818) 718-6300
20600 Prairie Street FAX: (818) 678-3740
Chatsworth, CA 91311-6008 e-mail:
[email protected] <mailto:[email protected]>
The suitability of this information for making decision is solely with the
reader
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