North American Network Operators Group
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Re: WLAN shielding

  • From: Howard C. Berkowitz
  • Date: Tue Dec 02 16:57:23 2003 
At 9:06 PM -0500 11/26/03, David Lesher wrote:

Speaking on Deep Background, the Press Secretary whispered:


 My company is investigating the use of wireless in a couple of our
 conference rooms.  Aside from limiting the scope of reception with various
 directional antennae, does anyone have any suggestions or pointers for
 other ways to limit the propagation of signals (i.e. special shielding
 paint, panels or other wall coatings)?

As I told Andy, you need a "RayProof" or similar brand shielded
conference room. This is Faraday Cage, with a tight-fighting door,
etc.

I don't know what they cost, but I've installed one or 2. Outside
of labor, I suppose they might be in the $50-500K range or so,
for small (12'x6') ones.

Note it's a PITA to keep tight; as the door needs very
tight-fitting gaskets.

You'll need to bring phone/Ethernet in over fiber,
but that's not hard.
If you do put one in, and your local laws don't prevent smoking, make it an absolutely no-smoking area. Ventilation tends not to be wonderful.

I was once attending a Federal Telecommunications Standards Committee meeting, where we were displaced from our regular conference room and given a SCIF vault/conference room. It was stuffy enough as we met for a couple of hours, but as we adjourned, the NSA representative lit a cigar.

That's when we found out that the vault door was jammed.

No simple cipherlock. Full combination lock. Trust me. Do not ever get in a mostly-sealed room with a dead cigar and some smoke remnants. When we got out, maybe two hours later, our faces matched the government green [1] walls. If this hadn't been in the then-Defense Communications Agency headquarters with resident locksmiths, I don't know how long we'd have been there!

Seriously, give ventilation a lot of thought. You'll need ducts with grounded screening and lots of 90-degree bends.

Also, consider having a kick-out panel for emergency escape. Even without high-security locks, I've seen the gasketed doors get stuck just in shielded labs. Think of fire protection -- you really don't want a fire suppression gas release in a vault.


[1] I believe the proper descriptor for that shade of green is "gang".