Gary,
The waveguide beyond cutoff attenuation will be very degraded by the cable
passing through it. It will become a length of coaxial cable.
The best thing I think would be bulkhead connectors that GND the entire
perimeter of the cable shield to the chamber wall.
The suggestion made by others of placing ferrites over the shield will
attenuate the current if they are placed at the low impedance areas. These
areas will move with frequency and you might want to use dozens of ferrites.
The waveguide beyond cutoff would work if the cable was a non-conductive
optical cable. In this case the I.D. should be less than one-half wavelength
and the length should be at least 4X the I.D. At 18 GHz the I.D. must be less
than 8 mm or 200 mils.
Another method is to cover the cable with another shield. Braid from RG-213
might fit or copper tape will work. Then bond this added shield to the chamber
wall where it passes through to the other side.
Dave Cuthbert
Linear Technology Colorado Design Center
LINEAR TECHNOLOGY CORPORATION
Internet Email Confidentiality Footer
This e-mail transmission, and any documents, files or previous e-mail messages
attached to it may contain confidential information that is legally
privileged. IF you are not the intended recipient, or a person responsible for
delivering it to the intended recipient, you are hereby notified that any
disclosure, copying, distribution or use of any of the information contain in
or attached to this transmission is STRICTLY PROHIBITED. If you have received
this transmission in error, please immediately notify me by reply e-mail, or
by telephone at (719)593-1579, and destroy the original transmission and its
attachments without reading or saving in any manner. Thank You
_____
From: [email protected] [mailto:[email protected]] On Behalf Of McInturff Gary
Sent: Wednesday, August 30, 2006 12:52 PM
To: [email protected]
Subject: Chamber transition panels
Dumb question maybe
I have to get a UTP Ethernet connection out of a semi-anechoic
chamber. There no anti-chamber so any unfiltered cable routing opening is a
major leak because of the opening and the induced noise on the cable itself.
Since Ethernet signals don’t like to be filtered. I’m considering two
options – neither of them make me real happy.
1) Find, if one exists, some sort of metallic RJ-45 bulkhead transition
connectors and mount that into the transition panel. I’ve seen the plastic
versions for inter-connecting Ethernet cables, but the were neither metallic
nor bulkhead mounted.
2) Make an air dielectric waveguide out of foot or so ½ inch metal pipe and
attach that to the transition panel and route the cable through the “wave
guide” The opening itself even at ½ is larger than 18 GHz upper test
frequency, but the width of the wave guide buys me some attenuation – and I
don’t expect to see much in the way of ambient up that high anyway.
I don’t have an option of putting the test gear into the chamber with the
EUT. The test gear would be a worse problem.
I don’t think this is completely brain dead but don’t see any easier
solution, but this doesn’t address any induced ambient noise on the cable.
Your thoughts?
Thanks
Gary
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please visit http://www.messagelabs.com/email
______________________________________________________________________
- ---------------------------------------------------------------- This
message is from the IEEE Product Safety Engineering Society emc-pstc
discussion list. Website: http://www.ieee-pses.org/
To post a message to the list, send your e-mail to [email protected]
Instructions: http://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas [email protected] Mike Cantwell [email protected]
For policy questions, send mail to:
Jim Bacher: [email protected] David Heald: [email protected]
All emc-pstc postings are archived and searchable on the web at:
http://www.ieeecommunities.org/emc-pstc -
---------------------------------------------------------------- This message
is from the IEEE Product Safety Engineering Society emc-pstc discussion list.
Website: http://www.ieee-pses.org/
To post a message to the list, send your e-mail to [email protected]
Instructions: http://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas [email protected] Mike Cantwell [email protected]
For policy questions, send mail to:
Jim Bacher: [email protected] David Heald: [email protected]
All emc-pstc postings are archived and searchable on the web at:
http://www.ieeecommunities.org/emc-pstc
