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?

Thanks

Why not control the PPC remotely using software such as SOTi Remote
Controller? Then you could szeal the PPC in the biscuit tin and have only a
single cable to the PC?

--
Darren Griffin
PocketGPSWorld - www.PocketGPSWorld.com
The Premier GPS Resource for News, Reviews and Forums