Won't the manufacturer tell you?
Best wishes
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK
On 2019-08-13 15:27, Ken Javor wrote:
Re: [PSES] GTEM cell used for RE measurement I understand how the GTEM
cell works for immunity. That is quite simple, as you say. It’s not as
simple for emissions. I think an analogy is the equation for
transmitting from an antenna is not reciprocal with receiving. One is
simply a function of gain, the other involves frequency/wavelength. I
too worked with GTEM cells in the past and understood better, and I
too did a search and found the very complex formulae (!) but now I
need to be able to get from a field intensity limit to the coupled
potential at the cell coax connector, and I’m not finding that, nor a
way to get there.
Ken Javor
Phone: (256) 650-5261
------------------------------------------------------------------------
*From: *"James Pawson (U3C)" <ja...@unit3compliance.co.uk>
*Reply-To: *"James Pawson (U3C)" <ja...@unit3compliance.co.uk>
*Date: *Tue, 13 Aug 2019 07:47:56 +0100
*To: *<EMC-PSTC@LISTSERV.IEEE.ORG>
*Subject: *Re: [PSES] GTEM cell used for RE measurement
Hello Ken,
Thinking aloud here: would such a factor exist as a generic formula?
If I think about this the other way round, putting 1V of RF into the
coax connector will generate 1V between the septum and ground (or
between the septums? septii? in the case of a differential GTEM like a
Laplacell).
This 1V will be spread over the distance between septum and ground,
dictating the overall field strength. This means cells with different
dimensions will have different factors. This is leaving aside the
frequency response / VSWR of the cell.
I do recall seeing some formulae for correlation between GTEM and
OATS/SAC but that was a while ago. A quick google on the subject shows
a few papers with lots of big equations.
I no longer have my old copy of EN 61000-4-20 but there might be some
interesting reference material in there. This standard also notes that
many of its provisions only apply to “small EUTs” which is anything
below a certain size in relation to the GTEM volume *or anything with
cables attached* (which are “under consideration”)
More practically, you could generate your own factors using an RF
generator and an isotropic field probe and using reciprocity to flip
this around to get a Volts out – field inside factor.
Additional: There’s also this NPL / York EMC guide on “The Use of GTEM
Cells for EMC Measurements” which has some interesting info in. Its
been a long while since I’ve read it in any depth though.
https://www.npl.co.uk/special-pages/guides/gpg65_gtem
Hope some of this is useful.
All the best
James
James Pawson
EMC Problem Solver
*
Unit 3 Compliance
*Design for EMC / Pre Compliance / Problem Solving / EMC Testing /
Consultancy / Environmental & Vibration
www.unit3compliance.co.uk <http://www.unit3compliance.co.uk/>
<http://www.unit3compliance.co.uk/> -- 07811 139957
Opening Hours: Tuesday to Friday, 0830 to 1800. Closed Monday.
*From:* Ken Javor <ken.ja...@emccompliance.com>
*Sent:* 12 August 2019 15:44
*To:* EMC-PSTC@LISTSERV.IEEE.ORG
*Subject:* [PSES] GTEM cell used for RE measurement
Does anyone out there have a simple transducer factor that yields rf
potential at the GTEM cell vertex coaxial connector for a given
vertical electric field component coupling to the cell septum?
Purpose is to calculate gain/noise figure specs for a preamplifier
used between spectrum analyzer and GTEM cell to measure RE.
Thank you.
Ken Javor
Phone: (256) 650-5261
-
----------------------------------------------------------------
This message is from the IEEE Product Safety Engineering Society
emc-pstc discussion list. To post a message to the list, send your
e-mail to <emc-p...@ieee.org>
All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html
Attachments are not permitted but the IEEE PSES Online Communities
site at http://product-compliance.oc.ieee.org/ can be used for
graphics (in well-used formats), large files, etc.
Website: http://www.ieee-pses.org/
Instructions: http://www.ieee-pses.org/list.html (including how to
unsubscribe) <http://www.ieee-pses.org/list.html>
<http://www.ieee-pses.org/list.html>
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas <sdoug...@ieee.org>
Mike Cantwell <mcantw...@ieee.org>
For policy questions, send mail to:
Jim Bacher <j.bac...@ieee.org>
David Heald <dhe...@gmail.com>
-
----------------------------------------------------------------
This message is from the IEEE Product Safety Engineering Society
emc-pstc discussion list. To post a message to the list, send your
e-mail to <emc-p...@ieee.org>
All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html
Attachments are not permitted but the IEEE PSES Online Communities
site at http://product-compliance.oc.ieee.org/ can be used for
graphics (in well-used formats), large files, etc.
Website: http://www.ieee-pses.org/
Instructions: http://www.ieee-pses.org/list.html (including how to
unsubscribe) <http://www.ieee-pses.org/list.html>
<http://www.ieee-pses.org/list.html>
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas <sdoug...@ieee.org>
Mike Cantwell <mcantw...@ieee.org>
For policy questions, send mail to:
Jim Bacher <j.bac...@ieee.org>
David Heald <dhe...@gmail.com>
-
----------------------------------------------------------------
This message is from the IEEE Product Safety Engineering Society
emc-pstc discussion list. To post a message to the list, send your
e-mail to <emc-p...@ieee.org <mailto:emc-p...@ieee.org>>
All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html
Attachments are not permitted but the IEEE PSES Online Communities
site at http://product-compliance.oc.ieee.org/ can be used for
graphics (in well-used formats), large files, etc.
Website: http://www.ieee-pses.org/
Instructions: http://www.ieee-pses.org/list.html (including how to
unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas <sdoug...@ieee.org <mailto:sdoug...@ieee.org>>
Mike Cantwell <mcantw...@ieee.org <mailto:mcantw...@ieee.org>>
For policy questions, send mail to:
Jim Bacher <j.bac...@ieee.org <mailto:j.bac...@ieee.org>>
David Heald <dhe...@gmail.com <mailto:dhe...@gmail.com>>
-
----------------------------------------------------------------
This message is from the IEEE Product Safety Engineering Society emc-pstc discussion
list. To post a message to the list, send your e-mail to <emc-p...@ieee.org>
All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html
Attachments are not permitted but the IEEE PSES Online Communities site at
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used
formats), large files, etc.
Website: http://www.ieee-pses.org/
Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas <sdoug...@ieee.org>
Mike Cantwell <mcantw...@ieee.org>
For policy questions, send mail to:
Jim Bacher: <j.bac...@ieee.org>
David Heald: <dhe...@gmail.com>
