A passive repeater? Basically an antenna both inside and outside the
room joined by a piece of coax.. Yes it works. I had it working with my
2m HT inside the home unit with a yagi sitting at the end of the
hallway, coax connected to the 5/8 on the roof of the house. (Only used
the yagi cause it was handy) Maybe 2-3 S points better at the time.
(best guess)

One of our guys at work has a similar setup for his mobile phone on
1800Mhz at his home QTH in a valley. Since we install mobile phone sites
I guess he would know.. He goes from no signal to noise free, how ever
many dB that is. Uses two mobile whips and about 10m of RG58 (yuk!)

Of course you'll have some losses in the system. Try it! Just remember
that coax losses on phone frequencies are kind of high so I suggest you
put the external antenna into a strong signal and think about using
lower loss cable. The trick is to experiment until you get a good enough
signal to use! (Unlike others I assume you want more than one phone to
work inside the room and that it needs to be portable)

I wont make any comments about filling the shielded room with other signals!

Repeaters are a little expensive but they do exist. We often do installs
in shopping centres, underground railways and high rise buildings using
such equipment. (Where you actually want a small coverage area) I am
pretty sure you can get an active wide band repeater as well. Since the
phone uses separate TX and RX freqs and you have a shielded room you
could get away with an amplifier running in each direction. (We did that
also for a UHF voice repeater on 400MHz with 5.5MHz separatation - in a
tunnel) Need a good set of cavities though. The installs that we do are
often extended using optical fibre at the RF frequency with antenna
interfaces at the remote end. You are talking a few bucks here by the
way. Go and have a look at Nokia's website if the passive one fails..

Cheers Bob VK2YQA

Rocco wrote:
Hi,
I have to provide mobile phone signal in a shielded environment.
Maybe the only way is by using an antenna that capture a sufficiently
strong signal outside the shielded room, and conveying that signal (
using a coax-cable ) inside it, at the end of the cable some sort of
repeater that provide the diffusion.
Does anyone has some other suggestion?
Or if the idea is correct, are those repeater in commerce?
And about the receiving antenna?
Thanks in advance.

RoS