Welcome to the group! We are all still clueless on this topic to
one degree or another. And the only stupid questions are the ones
that do not get asked.
I am the author of one of the loop antenna pages:
I have been told that my presentation is easy enough for novices,
but the page assumes some type of electronic knowledge on the part
of reader. I will try to make this simple.
First off, congratulations on your success with FM stations. It
shows real initiative on your part, and good deal of electronically
oriented intuition to go as far as you did and successfully receive
stations. As for the little indoor FM antennas - forget them. You
will receive far more stations by buying one of the FM "T-wire" type
antennas that may have even come with the radio. They are a dollar
or two, usually made of flat, clear wire that is about 3/8 of an
inch wide. You can probably find them at Walmart or Target, wrapped
up in a package hanging on the wall in the electronics accessory
department. Radio Shack or Best Buy will have them as well. Take
the wire out of the package, and you will find that it is shaped
like a "T", with connections for the screws of your stereo on the
bottom of the T. You will get the best reception if you use push
pins and install it at the ceiling on a wall that is closest to
broadside to the stations you want to receive. Please be careful on
the ladder! I get very good reception of stations up to 60 miles
away using one.
The next step up in FM antennas can be found at Radio Shack - they
have a 6 element FM antenna for around $25. I used mine to receive
stations up to 180 miles away. An outdoor antenna can be hidden in
an attic, and is certainly more trouble than the T-wire, but
sometimes that is the only way to receive stations.
Now, for AM loops - the main subject of this group. Without getting
into electronics terminology - the way the loop antennas we build
work is by taking advantage of the fact that two types of electronic
components - inductors and capacitors - both store electricity, but
do it in different ways. When you hook them together, they get
caught in a tug of war - transferring energy from one to the other -
at a specific frequency. That frequency is determined by the value
of each. The reason why your AM reception is so weak is that one of
them - the inductor (or coil of wire) is the wrong value. Your
capacitor is inside of your radio, so you have to match it. Right
now, it is not able to transfer energy back and forth at the same
rate as the stations are broadcasting, because the loop part is not
right. You may already know that an antenna made for UHF TV
stations probably would not work for VHF TV or FM, neither would an
antenna made just for FM work very well with UHF TV. It is exactly
the same principle the AM loop. You have to construct it correctly
to receive AM stations in conjunction with the capacitor inside your
radio.
Now, for a simple construction project. A lot of us have had
success with a Pizza box, but anything of that general size will
work. Styrofoam out of TV box, for example. Just something that
makes a big square or circle, and is not made of metal. It will be
near your radio, so you might want something that isn't too ugly!
14 by 14 inch square is fine. 20 by 16 inch rectangle is fine. 18
inch round is fine.
Next, you need to buy about 150 feet of wire. Home Depot and Lowe's
have packages of 50 feet or 100 feet, you will probably have to
twist shorter pieces together to make 150 feet. Copper wire is
best, it doesn't have to be thick or heavy or anything like that.
Insulated wire is best, but you may not have a wire stripper to deal
with it. It does have to conduct electricity efficiently when
twisted together. Steel or aluminum wire is not good.
Wrap all 150 feet around whatever it is you have for a frame. You
need to separate each turn of wire a little bit, so it doesn't short
against the next turn of wire.
I have purposely had you make an antenna that is a bit too "low" in
frequency - but it may work satisfactorily just as is. Each end of
the wire you wound around the box (or whatever you used) goes to a
screw on the radio.
If you aren't getting good reception, make sure the antenna is
standing up vertically and not flat (like it was on the floor). You
can also try turning it, loops are directional and this type is most
sensitive along its edge. Finally, you can try taking turns of wire
off, one at a time, until you get the best reception. My guess is
no more than 3 or 4 if you used a pizza box. If you take off too
many, you can twist it together again and add back a turn of wire.
When you get it the way it works best, use some tape to keep the
wire in place on the box.
Please let us know how it works, we are here to help you if you need
more advice!
