pstc list emc-p...@ieee.org
Subject: Re: ??? RE: ??? RE: Near field H-field measurement.
Ken Javor wrote
The only practical solution is to use a
probe that looks like the one the victim of rfi is going to be using,
connected to a receiver of equal to or greater sensitivity than the victim
).
IMO, such test would only be for very special circumstances and do not
warrant standardization as routine requirements.
From: Bob Richards b...@toprudder.com
Date: Fri, 24 Jun 2005 05:04:55 -0700 (PDT)
To: emc-p...@ieee.org
Subject: Re: ??? RE: ??? RE: Near field H-field measurement
Compliance Engineering
Tyco Safety Products / Sensormatic
6600 Congress Avenue
Boca Raton, FL 33487 USA
561.912.6440
djumbdenst...@tycoint.com
From: Bob Richards [mailto:b...@toprudder.com]
Sent: Friday, June 24, 2005 8:05 AM
To: emc-p...@ieee.org
Subject: Re: ??? RE: ??? RE: Near field H
Ken,
I'm no expert, but as I understand it, making
measurements at low frequencies, measured in the near
field, it is possible to have a very high E-field and
very low H-field if the radiating source is high
impedance. The opposite is true if the radiating
source is low impedance, ie: high
Ken Javor wrote
The only practical solution is to use a
probe that looks like the one the victim of rfi is going to be using,
connected to a receiver of equal to or greater sensitivity than the victim,
and similar bandwidth, and verify that the level of rfi at a particular
separation is
: ??? RE: ??? RE: Near field H-field measurement.
Bob Heller asked:
How would one go about accurately measuring low frequency fields say at
10
kHz where the far-field even at lambda/6 is 5000 meters?
Accuracy and what regulatory authorities require are not always the same
thing. It isn't
is
only appropriate if a far field measurement is possible.
From: Iain Summers iain.summ...@blueyonder.co.uk
List-Post: emc-pstc@listserv.ieee.org
Date: Thu, 23 Jun 2005 21:44:27 +0100
To: emc-p...@ieee.org
Subject: Re: ??? RE: ??? RE: Near field H-field measurement.
Ken very succinctly put. I
politicians don't do EMC.
Iain
- Original Message -
From: Ken Javor mailto:ken.ja...@emccompliance.com
To: emc-p...@ieee.org
Sent: Thursday, June 23, 2005 9:05 PM
Subject: Re: ??? RE: ??? RE: Near field H-field measurement.
There is a significant over-generalization here
...@comcast.net
List-Post: emc-pstc@listserv.ieee.org
Date: Thu, 23 Jun 2005 18:56:33 +
To: emc-p...@ieee.org
Subject: RE: ??? RE: ??? RE: Near field H-field measurement.
By measuring the E and H components separately, using near-field probes, which
are, in principle, electrically short dipoles
Message-
From: Bob Richards [mailto:b...@toprudder.com]
Sent: Thursday, June 23, 2005 7:06 AM
To: emc-p...@ieee.org
Subject: Re: ??? RE: ??? RE: Near field H-field measurement.
Ken,
I believe you are correct. There should be factors for this
loop antenna from Emco that convert the raw
-Original Message-
From: Bob Richards [ mailto:b...@toprudder.com]
Sent: Thursday, June 23, 2005 7:06 AM
To: emc-p...@ieee.org
Subject: Re: ??? RE: ??? RE: Near field H-field measurement.
Ken,
I believe you are correct. There should be factors for this
loop antenna from
...@toprudder.com
Date: Thu, 23 Jun 2005 07:05:43 -0700 (PDT)
To: emc-p...@ieee.org
Subject: Re: ??? RE: ??? RE: Near field H-field measurement.
Ken,
I believe you are correct. There should be factors for
this loop antenna from Emco that convert the raw
reading (in dBuv) to a magnetic field level (like
...@assaabloyitg.com
Cc: emc-p...@ieee.org
Subject: ??? RE: ??? RE: Near field H-field
measurement.
Dear Dave,
Thanks for your information.
Since the local regulatory body set both E-Field AND
H-Field limit for
frequency range under 195kHz. But as I know, for all
radiated emission
leungderek2...@yahoo.com.hk
List-Post: emc-pstc@listserv.ieee.org
Date: Thu, 23 Jun 2005 11:41:41 +0800 (CST)
To: fdev...@assaabloyitg.com
Cc: emc-p...@ieee.org
Subject: ??? RE: ??? RE: Near field H-field measurement.
Dear Dave,
Thanks for your information.
Since the local regulatory body set both E
Dear Dave,
Thanks for your information.
Since the local regulatory body set both E-Field AND H-Field limit for
frequency range under 195kHz. But as I know, for all radiated emission
measurement under 30MHz should use loop antenna, so I use EMCO 6502 for E and
H- fields measurement.
The
Derek,
in regards to the magnetic field measurement from 50 kHz to 1 GHz:
You can figure that your measurement is in the far-field when the distance is
1/6 wavelength. At a distance of 10 meters this occurs above 5 MHz. So above 5
MHz the field will drop as 1/d and the difference between 300
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
...@ieee.org] On Behalf
Of Robert A. Macy
Sent: Tuesday, June 21, 2005 8:58 AM
To: Y W Leung
Cc: emc-p...@ieee.org
Subject: Re: Near field H-field measurement.
Near field?! You're way inside near field below 200KHz.
At those fundamental frequencies, you are correct.
Magnetic fields drop at the rate
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
_
From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org] On Behalf Of
Ken Javor
Sent: Tuesday, June 21, 2005 9:19 AM
To: emc-p...@ieee.org
Subject: Re: Near field H-field measurement.
A limit specified at 300 meters is outside my experience. I have seen limits
at 1 m (military ), and 3
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
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