"Roger Halstead" wrote in message
...
On 14 Jan 2004 11:54:38 -0800, (Rocco)
wrote:

I'm basing my answer on the subject line word "hard" and the "shielded
environment" statement below.

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 (

If it is truly a shielded room...forget it.
It was shielded for a reason and you used the term "hard" suggesting
it was intended to be shielded. Causing that shielding to fail could
be grounds for hunting for a new job.

using a coax-cable ) inside it, at the end of the cable some sort of
repeater that provide the diffusion.

IF you could get a passive repeater to work you would be causing a
loss of integrity to the shielded room. I've never gotten a passive
repeater to relay a signal strong enough to be useful.

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.

Unless, contrary to your phrasing the room is not shielded by intent
you really need to forget the whole thing.

I used to have a work area in a double walled shielded cage. When the
door was closed we could take 5 watt HTs less than a foot apart... One
outside and one inside. We could see and hear each other through the
screen but the HTs could not. Anything that could have let a signal
in would have negated the purpose of the room.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com


RoS



I regularly use passive and active "repeaters" to convey RF signals into a
shielded enclosure.

Sometimes, I'm testing a system that requires a GPS signal. I use an active
GPS antenna on the roof of my building, a 75-foot run of semi-rigid coax,
and then into a low-noise pre-amp. The output of the pre-amp goes to a
coaxial feedthrough port, and, on the inside of the chamber, I mount a
passive GPS antenna (as a radiator). The active GPS antenna has a very
narrow bandwidth, so out-of-band signals are reasonably well rejected and
not imported into the chamber.

Other times, I may be testing a device with a VHF / UHF data link. I usually
just put a simple rod antenna in the chamber, mounted directly to the coax
feedthrough port. Outside the chamber, I run coax to a test set / simulator,
or I connect another rod antenna. True, this introduces more RF garbage into
the chamber, but, if it becomes a problem, I can just stick a band-pass
filter into the coax line. Works every time for me.

Ed
wb6wsn