Reception in a tin can
 

My office is located in a metal warehouse type structure which
effectively shields us from most outside signals. If I want to listen
to the radio or use my cell phone inside the building I have to open a
bay door. Is there a way I can get all those radio waves inside the
building without opening the doors. Is it possible to place an
antenna outside and have everything rebroadcast inside? The main
reason for this approach is the cell phone. It would be kind of
impractical to run an antenna from my cell phone to the outdoors.

Barring the rebroadcasting idea, I am still interested in what the
best way is to get better reception on the radio. Do I need to run a
wire outside or somehow ground the radio. Go easy on me, I've heard
some stuff about 7mhz being 23 feet long at a quarter wave. If your
gonna spring some of that stuff on me I need a little more detailed
information. I'm not up on radio lingo but I am technically capable.

TIA
The Bad Priest

My office is located in a metal warehouse type structure which
effectively shields us from most outside signals. If I want to listen
to the radio or use my cell phone inside the building I have to open a
bay door. Is there a way I can get all those radio waves inside the
building without opening the doors. Is it possible to place an
antenna outside and have everything rebroadcast inside? The main
reason for this approach is the cell phone. It would be kind of
impractical to run an antenna from my cell phone to the outdoors.

Barring the rebroadcasting idea, I am still interested in what the
best way is to get better reception on the radio. Do I need to run a
wire outside or somehow ground the radio. Go easy on me, I've heard
some stuff about 7mhz being 23 feet long at a quarter wave. If your
gonna spring some of that stuff on me I need a little more detailed
information. I'm not up on radio lingo but I am technically capable.

While it may not work for you , look up "passive repeater" This is an
antenna aimed at the desired station (on the outside of the building in your
case) and a feedline inside the building hooked to another antenna.

For receiving other frequencies you may have to run a wire outside the
building and either hook it to the receiver or wrap it around the receiver.

I have not seen it but have heard that in long tunnels they have an outside
antenna and an amplifier and some inside antennas for the FM radio stations.

The passive repeater is an excellent idea. I have done that extensively at
Radio Shack. We had a TV antenna outside for the TV signals. We would be
sure to run a feed-line to the inside TV demo antenna, and to a automobile
antenna in the "car sound" display. We could then give relatively accurate
demonstrations of the small transistor radios and auto stereos. You
wouldn't believe it, or won't believe it until you try it. Two antennas
connected by as sort a feed-line as possible.

--
73 es cul

wb3fup
a Salty Bear

"Ralph Mowery" wrote in message
...
My office is located in a metal warehouse type structure which
effectively shields us from most outside signals. If I want to listen
to the radio or use my cell phone inside the building I have to open a
bay door. Is there a way I can get all those radio waves inside the
building without opening the doors. Is it possible to place an
antenna outside and have everything rebroadcast inside? The main
reason for this approach is the cell phone. It would be kind of
impractical to run an antenna from my cell phone to the outdoors.

Barring the rebroadcasting idea, I am still interested in what the
best way is to get better reception on the radio. Do I need to run a
wire outside or somehow ground the radio. Go easy on me, I've heard
some stuff about 7mhz being 23 feet long at a quarter wave. If your
gonna spring some of that stuff on me I need a little more detailed
information. I'm not up on radio lingo but I am technically capable.

While it may not work for you , look up "passive repeater" This is an
antenna aimed at the desired station (on the outside of the building in
your
case) and a feedline inside the building hooked to another antenna.

For receiving other frequencies you may have to run a wire outside the
building and either hook it to the receiver or wrap it around the
receiver.

I have not seen it but have heard that in long tunnels they have an
outside
antenna and an amplifier and some inside antennas for the FM radio
stations.

On Thu, 28 Aug 2003 12:42:15 -0400, "Ralph Mowery"
wrote:


While it may not work for you , look up "passive repeater" This is an
antenna aimed at the desired station (on the outside of the building in your
case) and a feedline inside the building hooked to another antenna.

In most cases you have to be quite close to the indoor antenna (within
a few meters), since the signal reradiated from the indoor antenna is
suffering an additional inverse square attenuation.

The worst situation for a passive repeater system is when the repeater
is in the mid path with the end stations A and B. The path losses
(expressed in decibels) from A to the repeater and from the repeater
to B are _added_. Compare this to the free space (line of sight
situation) in which the total path loss from A and B is only 6 dB more
than compared to the path loss for A to the mid point repeater
location.

In a passive repeater system, moving the repeater closer to the other
station, the sum of the path losses from A to the repeater and from
the repeater to B (expressed in decibels) will be smaller than with a
repeater in the mid path.

I have not seen it but have heard that in long tunnels they have an outside
antenna and an amplifier and some inside antennas for the FM radio stations.

Leaky coaxial lines are used as "antennas" in tunnels.

Paul OH3LWR

I've never had any luck using just one can. You could tie the string to a
doorknob and use just one can - but what are you going to hear on it?

To make it work, have another can on the far end of the string, with someone
speaking clearly into the can. Remember to keep the audio transmission line
taut for best reception.

Charles Brabham, N5PVL

Your tin can will work much better if you add a piece of tissue a coil
of wire and a magnet. I don't know why no one ever mentions that when
talking about the finer points of tin can technology.

Well I guess a passive repeater was exactly what I was thinking of and
it sounds like it works about as well as one would expect. Is there
such a thing as an active repeater? Is there some way that I can
amplify all of those signals. Can I broadcast all frequencies all the
time?

Also, I'm still interested in grounding. I've been noticing the
effects of grounding more and more lately. I just realized that my
house isn't really grounded (as far as I can tell anyway). I've got
PVC plumbing and the electric box is just wired neutral to common.
Ever since I put a ball on my truck and wired up the trailer light
connecter I've gone from great reception on the radio to average or
poor. I think the trailer ground wire is acting like a maverick
antenna. We got a new forklift that has a fiber strap that drags
along the floor. I think the wheels are polyethelene or polypropoline
or something and without the strap the forklift can generate enough
static electricity to knock you on your ass. I lived in Okinawa when
I was a kid and a lot of the cars there had a rubber strap with a
little reflector that drug along the ground. The explanation at the
time was that the Japanese liked lights. I never did understand but
could it be to ground the vehicle and get better radio reception?
Should I drag a chain behind my truck for better reception? Also, the
radio at work; how should I set the antenna up. It's just two pieces
of wire tucked up into the ceiling tile. There is a copper compressed
air line running nearby that is not grounded directly (It is hung from
the structual steel but there is no direct copper to ground). I've
noticed that sometimes reception is a lot better if one or both ends
of the wire are touching this copper line. Is the antenna being
grounded or is it acquiring capacitance? WHat is the proper way to
ground it. Do you ever ground an antenna or do you just ground the
receiver?

Well that's probably too many questions already. I'm posting via
google so i have to wait 3 to 6 hours to see it.

Thanks,
El Malo

and not that anyone is going to tell me but what is 73?

El Malo,
The 'static' strap draggin on the ground is a terrible
idea. In most cases, it generates more static than it will
ever 'cure'. It's also dangerous, just like the fork lift.
The DOT prohibits static straps on commercial vehicles that
carry flamable/explosive materials (fuel trucks) because they
act as part of a "VanDegraff"(sp) generator. I'm sure a nice
fat spark is exactly what you want to see when connecting a
fuel line to a tank. (Also why fuel hoses at gas pumps are
grounded through the nozzle. And why fuel trucks at an air-
port always connect a ground line to the plane before fueling.)
'Doc