The Other Brian,

 

CISPR 22, Edition 5.0, Amendment 1 was published in 2005.  It added limits for
radiated emissions from 1 GHz to 6 GHz, along with the test method.  

 

The test method differs from ANSI C63.4.  No height scan of the antenna is
performed unless the EUT is taller than the 3 dB beam width of the antenna. 
RF absorbers are placed on the floor between the antenna and the EUT.  As long
as the absorbers work over the entire 80 MHz to 6 GHz frequency range I would
see no problem in using them for both emissions and immunity testing.  Also, I
personally don’t see a problem with their being installed when testing for
the FCC above 1 GHz.  ANSI C63.4 makes the statement that reflected emissions
>from the floor will not be measured due to the beam width of horn antennas. 
We know this isn’t really true, but if the standard assumes you won’t see
the reflected waves then suppressing them shouldn’t be an issue, now should
it?  :-)

 

Ghery S. Pettit

 

 

  _____  

From: [email protected] [mailto:[email protected]] On Behalf Of Kunde, Brian
Sent: Monday, December 10, 2007 8:34 AM
To: [email protected]
Subject: Setup for Emissions Over 1GHz

 

Group,

 

In a large chamber, is emissions testing over 1GHz performed in a "Free Space"
setup with absorbers on the floor or it is performed with a reflective floor
as has been the method for FCC for years now?  What is the current status in
this regards? Has a set test setup been established?

 

I am not an expert in CISPR22 or the latest CISPR16 standards. We exclusively
use CISPR11 to test ISM equipment which currently state that "Limits are
intended to be identical to the limits currently under Consideration for ITE
above 1GHz". Are these limits still under consideration and does the test
setup require absorbers on the floor? In other words, is emissions testing
performed in a Semi-Anechoic Chamber (SAC) or a Fully-Anechoic Chamber (FAC)
setup?

 

If floor absorber is required for emissions above 1Ghz, can the same material
be used for emissions AND immunity? If not, why? If so, what material do you
recommend and where can I buy it?  I need to order absorber material for
immunity and I would prefer to use something I can also use for emissions if
required.

 

Thanks in advance for all replies and any other information that will help me
understand the set setup requirements.

 

The Other Brian

 

 

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