warrenwolff@aol.com wrote:
> Hi again folks,
>
> Wow, I surely do stir up a hornet's nest when I pose some of my
> questions to this group.
>
> This subject of a Faraday?Shielded Room came up when I was
> trying to get this new house as protected as possible.? The almighty
> dollar interfered with some of my thoughts, this being one of them.
>
> I was suspecting that a bit less than 1/4 wave at 2 meters would have
> been sufficient for such a room.
>
>
More likely you'd want to go with something like 1/4" mesh. IOW heavy
duty, hot dipped galvanized hardware cloth (I've forgotten the proper
name for it). Then solder the edges together. It's stiff, bulky,
relatively heavy, and has lots of sharp points when cut, but it's heavy
enough to handle plenty of current and I'd bet it'd do the job. You
could probably to a whole room for a couple hundred dollars if
incorporated into the original construction. OTOH if incorporated into
an existing room you'd add the couple hundred dollars to the cost of
completely refinishing the room. Cover the hardware cloth with
plasterboard and flooring. Bond all joints and corners. The expensive
part would be the door area. Use a metal door with finger stock along
the edges of the door jam. put a continuous metal frame over the edges
around any window and then fit a copper screen. You'd have light, be
able to see out, and still have protection. When I worked in the double
walled screen room the door was the weak spot. It used large finger
stock and the door cammed shut. I mentioned being unable to hear a 5
watt HT a foot outside the room, but that was with the door cammed
shut. While the door could be shut, and all finger stock engaged you
could still hear the HT. ONLY when the door was cammed shut (and it had
additional wipers top, bottom and each side), did the HT's signal
disappear.
> Now David has dug up a reference:
>
>
> - Aperture
> Aperture
> An opening in a shielded enclosure that may become the source of leakage for
> electromagnetic energy. This is
>
> most common in joints, seams and penetrations such as switches, connectors,
> and lamps/LEDs. Typically, the
>
> maximum dimension of an aperture should be less than 1/20 wavelength of the
> highest frequency of interest in
>
> order to avoid emissions.
>
> Interesting, to say the least.
>
> The comments re: air conditioning resurrected an old experience(s).? When I
> was an OIC of a STRATCOM
> Receiver Site in Hawaii, we had a all copper screen room.? As Program Manager
> of a Comm System in
> Kuwait, we also had one.? In both cases, we did not close the door unless
> absolutely necessary because
> of poor air conditioning.
>
> Then it hit me; my project engineer from USAF days has a PhD in Physics.?
> Think I will
> ask him if 1/20 or 1/10 is overkill.? The idea of something less than the
> tightly closed
> copper mesh room still intrigues me - - IF the spacing is not too small.?
> Doorways and
> A/C ducts probably pose the biggest problem to a "cheapo" room.
>
> I appreciate all of the interest and the well-founded references provided so
> far.
>
> Warren; W7WY
>
>
>
>
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