Dear experts,
I am measuring the fundamental and spurious emissions from an EUT ( with
interanl loop antenna) of fundamental frequencies of about 50kHz to 200kHz.
The measuring range of spurious emission is up to 1GHz.
The limits are according to a local standard from a local regulatory
All things being equal (and of course, they never are), I would expect that
a plasma display would be noisier. The scan rates of the two displays are
equal, but the voltages swings are larger for a plasma display. Plus the
power is much higher for a plasma display - just stand near one and you
In general, is it possible to say which one that has the lowest radiation?
Cheers!
#Amund Westin
Oslo / Norway
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melli...@tycoint.com wrote (in
2141C5F52FD2CA4182AF6927090263B90F61B247@flbocexu04) about 'Status of
EN 55022', on Tue, 21 Jun 2005:
I know that over the last year there has been a lot of talk about the
[quickly] upcoming EN 55022 requirements on the OJ.
There had been some discussion
Derek,
The FCC specifies using a loop antenna for measuring field strength below
30 MHz. Extrapolation can be used if the field strength is measured at two
distances and the factor calculated (it will be close to 1/R^3), otherwise
the default of 40 dB/decade (1/R^2) must be used.
We normally
Derek and Robert,
The fields from an electric dipole drop off as:
Magnetic: 1/r^2 and 1/r
Electric: 1/E^3, 1/E^2, and 1/E
For a magnetic dipole (loop):
Magnetic: 1/r^3, 1/r^2 and 1/r
Electric: 1/E^2, and 1/E
This link provides the formulas that will allow to to calculate the
field strength
Forgot!
E Fields from a true dipole do drop off at the inverse cube
rate also, It's just that the fields almost always get
referenced to a ground or ground plane which makes them
drop off for all practical purposes at the rate of the
inverse square.
- Robert -
From: Y W Leung
Derek,
are your magnetic field measurements only in the range of 50 to 200 kHz? Or,
do you intend to measure to 1 GHz? If the former, you may need to modify your
300 to 10 meter scaling for specific frequencies between 50 and 200 kHz. I can
find you the formula for this. If the latter, you
Mr.. Leung,
At low frequencies, you may have undesirable effects from underground pipes /
etc... Or your EUT may be significantly large compared to the antenna to
influence the measurement. This makes the assumption of 3rd order rolloff
uncertain.
The FCC guidance is to measure at 2
Mr. Leung,
Here is an excerpt from the FCC Rules pertaining to measurements below 30 MHz
using a loop antenna.
At frequencies below 30 MHz, measurements may be performed at a distance
closer
than that specified in the regulations; however, an attempt should be made to
avoid making
A limit specified at 300 meters is outside my experience. I have seen limits
at 1 m (military ), and 3, 10, and 30 meters (commercial). I'm not sure how to
extrapolate below 30 MHz where you are using the EMCO loop. But above 30 MHz
where you are only measuring electric field, the extrapolation
Dear colleagues;
I would like to thank all those who replied to my predicament regarding
emissions from an Ethernet port.
I have had some first-class advice which will help me solve the problem.
Many thanks;
Ian McBurney.
Allen Heath Limited.
email: ian.mcbur...@allen-heath.com
***LEGAL
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