Reduce wireless signals
 

In article ,
(TMartin831) wrote:

http://informationweek.com/story/sho...cleID=56200676

By Jim Nash Dec. 28, 2004

A small startup in Silicon Valley has an anti-intrusion tool that
sells for $69 a gallon--you supply the brush.

Force Field Wireless makes three products that it says can
dramatically reduce the leakage of wireless signals from a room or
building. The company's sales manager, Harold Wray, co-developed
DefendAir Radio Shield latex paint, which contains copper filings and
an aluminum compound. When spread evenly on a wall, the paint
reflects signals in frequencies from 100 MHz to 5 GHz. Paint four
walls, a floor, and a ceiling, and you effectively have a Faraday
cage, which is a specially constructed metal room that blocks all
radio signals in or out, suitable for a CIA director or a determined
shut-in.

Not a new idea.

Snip

DefendAir is nontoxic, contains no lead, and meets all U.S.
Environmental Protection Agency standards, Wray says. Besides the
paint, Force Field sells 32 ounces of a copper/aluminum powder that
homeowners can add to their own paint for $34. The company also makes
a window film that cuts down on signal leakage: A 30-inch-by-25-foot
roll is priced at $45.

None of this is new.

Copper is toxic in power form. The paint will be toxic in the
environment.


"This wouldn't be the first thing I'd do to secure a network," says
Spire Security's Lindstrom. "But in a crowded environment, in an
office complex, it might be a thing to do." It's better to implement
a solid authentication/encryption system, he says.

Snip

This is a waste of time. You don't have a Faraday cage unless all
walls, floor and ceiling are shielded and you can't have gaps in the
shield.

Even worse than the gap problem is that signals can be carried in and
out of a shielded area through any conducting wire that penetrates the
cage through common mode coupling.

Shielded rooms need filtering on all conductors in and out of the room.
If this is not done you don't have a shielded room that either keeps
signals out or in.

--
Telamon
Ventura, California

A small startup in Silicon Valley has an anti-intrusion tool that
sells for $69 a gallon--you supply the brush.


....and money!

Snake paint - about as useful as those cell-phone RF brain radiation
shields.

does it only reflect rf? or is it conductive? i am studying on a
paint-on antenna system right now! heck, the perfect stealth antenna is
here! come on, there are SOME smart guys on this ng! lets get on this
project! hams are you interested? A CHEAP PAINT ON ANTENNA SYSTEM! the
ramifications are endless.

In article ,
(Jim) wrote:

does it only reflect rf? or is it conductive? i am studying on a
paint-on antenna system right now! heck, the perfect stealth antenna
is here! come on, there are SOME smart guys on this ng! lets get on
this project! hams are you interested? A CHEAP PAINT ON ANTENNA
SYSTEM! the ramifications are endless.

The paint is conductive if enough copper added to it. Chances are that
there will not be enough copper added for it to be conductive at zero
hertz but it does not have to in order to reflect short wave length RF.

For the conductive paint to make a spray on antenna it will need enough
copper in it to be conductive at DC. This is more practicable for an
antenna than spraying all surfaces of a room since that area is limited.
With enough copper in the paint on a good insulator you could make a
good antenna. You could use a small metal plate over the end of
the conductive painted area to transition through capacitive coupling
to coax to the radio.

--
Telamon
Ventura, California

There is a special kind of interior wall board that is available for
that purpose too.The CIA and some other govt places and outfits use it.I
don't remember the name of it or which company makes it though.But that
paint does sound interesting.
cuhulin

If anybody wants to snoop in my computer,I believe they will find it to
be very dull and uninteresting snooping.In fact,I might look around
somehere (a hospital,perhaps) and find some very ugly looking hemorroid
butt pictures for them to snoop at.
cuhulin