AM antennas inside steel buildings <again>
JAMES MCEWEN
A coworker wants to get AM radio inside our warehouse <steel
frame/steel sided building> Windows are armor glass with chicken wire
in them. I have looked at the Radio Land catalog, and they have 2
antennas for AM. The Select-a-tenna and the Terk AM Antenna. Neither
of these "antennas" require a connection to the receiver. So how do
they work? For an extra $30 they will supply a model with a ferrite
stick "coupler". These are all unpowered too.
Anyone know of a construction article for an AM antenna/ tuned
amplifier feeding a ferrite loopstick coupler?
As an aside, there are some neat old antenna systems offered on ebay
<with pictures sometimes>. Anyone know what an F&H Reesonator is? Or
how it was supposed to work? There is a picture on one on ebay right
now.
Thanks & 73's
Jim, KA6TPR
Cliff Holloway
outside and remote couple to the AM radio inside that would work. What I
had to do was place an old GE super radio in a "hot spot" and rebroadcast
the AM signal on a FM transmitter (from the C. Crane co @ about $30) to my
FM radio. I had to build a gain antenna for the transmitter to get a good
signal. This setup has worked very well. My problem was not just shielding
from the metal building but also high electrical noise from equipment.
Hope this helps....Cliff N0HC
JAMES MCEWEN <mcew...@songs.sce.COM> wrote in article
<9810089078....@ccgate.songs.sce.com>...
Gary Coffman
>Hi Jim, the select-a-tenna has a model that you can place the antenna
>outside and remote couple to the AM radio inside that would work. What I
>had to do was place an old GE super radio in a "hot spot" and rebroadcast
>the AM signal on a FM transmitter (from the C. Crane co @ about $30) to my
>FM radio. I had to build a gain antenna for the transmitter to get a good
>signal. This setup has worked very well. My problem was not just shielding
>from the metal building but also high electrical noise from equipment.
>
>Hope this helps....Cliff N0HC
Cliff's approach is probably the best one for the described situation.
To extend it a bit, you can place the GE Super Radio (probably about
the best AM radio available) *outside* in a plastic or wooden enclosure.
That will ensure good AM reception. Then run the audio in on a twisted
pair to the FM rebroadcaster inside the metal building. If you locate
that in a good spot, you can use a Walkman style FM portable nearly
anywhere inside the building. The only downside is that you'd need
to go outside to change the station on AM. But there's probably only
one station you want to hear anyway, so that usually won't be a
problem.
There is another alternative, but it can be tricky to implement.
You can erect an outdoor antenna and rebroadcast the entire
AM band into the building using a broadband amplifier and an
indoor antenna. This approach lets you use your AM radio
normally indoors, but there are lots of potential problems
ranging from overload of the amplifier by several strong
broadcast signals to feedback oscillation due to coupling
between the two antennas. With a well shielded building, it
should work though.
Gary
Gary Coffman KE4ZV | You make it |mail to ke...@bellsouth.net
534 Shannon Way | We break it |
Lawrenceville, GA | Guaranteed |
Richard Harrison
You can erect an outdoor antenna and rebroadcast the entire AM band into
Gary noted the potential oscillation problem. This problem can be
avoided by rebroadcasting inside the building on offset frequencies.
Either a remodulating or a heterodyne repeater could accomplish this.
Either method would require careful suppression of incoming signals so
as not to rebroadcast them too.
Best regards, Richard Harrison, KB5WZI