Hans,
There are professional techniques for using Aluminum foil to shield a
room, and the trick is to treat the seams and penetrations.
Penetrations should be installed on a conducting plate (AL to match the
foil shield, but galvanized steel should be OK), and should use filtered
or shielded wiring. This website shows AL foil specifically for room
shielding, and shows depictions of seam treatment.
http://www.ramayes.com/aluminum_foil_emi_rfi_shielding.htm
Here are the seaming methods for AL foil (in order of effectiveness:
1. 3" overlap
2. No overlap, 6" AL seaming tape
3. 3" overlap plus 3" seaming tape
4. 4" wide aluminum tape that has a conductive adhesive.
I have also seen claims of good results using a folded seam.
But for lightning, the best thing you can do is to implement a single
point ground. This is a conductive panel to which all wiring and
cabling goes to before going anywhere else and has surge/lightning
protection and shield bonding, and which has an excellent grounding
bond. LIghtning is much more likely to follow a conductor into the
shack than penetrate a non-conducting wall or roof.
73,
Avery, WB4RTP
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