DIY Faraday cage for a mobile phone

"Skier" <[email protected]> wrote in message
news:[email protected]...
> "Simon" <[email protected]> wrote in message
> news:[email protected]...
> > 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
> >
>
> I would use the tin idea with a small hole cut and connect the USB cable
and
> then use "active sync remote display" to control and view the screen.
Easy!
>
> Then you can chop the tin up and creat some leaks to simulate different
GPRS
> strength.
>
> Paul
>
>

Thanks for all the replies. I think I will seek out some finer mesh and try
the cage route again. The cage built out of 12mm mesh does decrease the
reading on the signal-strength icon, so I think smaller mesh may do the
trick.
I tried some other things, with limited success:
- I have tried disconnecting the internal antenna, but the connector is a
tiny coax connector about 2mm in diameter, which will almost certainly break
after a few repetitions.
- I don't want to activesync to the device under test, as that has an effect
on the network configuration of the device. In fact, the device stops using
GPRS altogether and sends its network traffic over the activesync cable.

---

› See More: DIY Faraday cage for a mobile phone

[email protected] declared for all the world to hear...
> - I don't want to activesync to the device under test, as that has an effect
> on the network configuration of the device. In fact, the device stops using
> GPRS altogether and sends its network traffic over the activesync cable.

Only if you allow it to. Open activesync and un-check the "passthru"
mode.
--
Regards
Jon

Why not just download the Pocket PC remote viewing/control software from
Microsoft and operate it in the tin from a locally connected PC?

[email protected] declared for all the world to
hear...
> Why not just download the Pocket PC remote viewing/control software from
> Microsoft and operate it in the tin from a locally connected PC?

What software is this you speak of?
--
Regards
Jon

Jon wrote:
> [email protected] declared for all the world to
> hear...
>> Why not just download the Pocket PC remote viewing/control software from
>> Microsoft and operate it in the tin from a locally connected PC?
>
> What software is this you speak of?

Remote Display Control for Pocket PC

http://www.microsoft.com/technet/pro...ctoys.mspx#ELD

"Simon" <[email protected]> wrote in message
news:[email protected]...
> 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
>
>

Thanks for all the replies, I have put together a webpage at
http://www.sgurr.co.uk/lundycam/faradaycage.html
describing the faraday I eventually built, based on biscuit tin and chicken
wire technology. It does block GPRS signals.