In article
Simon wrote:
Hello -

I'm writng some software to run on a PocketPC with a built-in GPRS phone,
and I need to test the software when the GPRS signal is weak, intermittent
or non-existent. The cheapest way to do this seems to be to build a Faraday
cage with adjustable leakiness. It needs to have some holes in it so that I
can see the screen and tap it with a stylus. Unfortunately I'm working at a
location that has excellent GPRS coverage.

I've already confirmed that a metal tin that previously contained Marks and
Spencers chocolate biscuits is 100% effective, but I can't see through it or
operate the PocketPC. I've also tried making a cage out of a single sheet of
galvanized chicken wire with 12mm square holes, held together with plastic
cable ties, with overlapped joints. This only caused a small amount of
attenuation, the PocketPC hardly noticed. I'm guessing that it failed
because the diagonals of the holes are larger than 10% of the wavelength
that GPRS uses (1800MHz ?) or because the plastic cable ties don't provide
good conductivity at the joints.

Before I go out and buy some expensive perforated copper sheet, can anyone
offer advice on improvements?

Get a large cardboard box (or old wardrobe), wrap it in kitchen foil and
sit inside it. :-)