This is Bruce (not Brian) Carter. My opinion on those little loops
that come with receivers is that they are probably NOT tuned loops
with the varactors or tuning capacitor inside the units. I think
that they are de-tuned badly to allow broadband reception, and then
they make up the difference by using a lot of gain on the front
end. If they are tuned, any loop with the same inductance should
track with their internal capacitance. Since they are rectangular,
you would have to use my new formula (which is not on the loop
antenna page yet, but is on my work page at:
kb=analog&obj=498
You will have to cut and paste that URL. You can also get there by
going to www.ti.com/amplifier_utilities and clicking the design
calculator link at the bottom. The loop antenna stuff is really
intended for a line of chips for wireless keyboards and mice, but it
works very well for AM antennas as well. Once you get the correct
inductance from the dimensions and number of turns of your antenna,
design a bigger one for the same inductance and you should be fine.
--- In loopantennas@..., "Michael Hebert" <qrpbear@y...>
wrote:
Chris,
Check out Brian Carter's web page at...
<>
for a very simple and effective AM loop antenna.
What most people don't realize about those AM loop antennas that
come
with stereo receivers is that are not always meant to be used as
they
are. Quite often you get better results if you unwind them and
string
the wire around the room (or even along the baseboard).
73,
'Bear' NH7SR
--- In loopantennas@..., "lockmanslammin"
<lockmanslammin@a...> wrote:
I have a yamaha reciever, that has an am antenna hookup with
an "in"
and a ground. It came with a small plastic loop antenna, that
doesn't
quite seem to get the station I want. So i searched am antennas
online to find LOTS of info, and some plans, but they all seem
to
be
to big or overly complex for my needs. what I'm looking for is
plans
for an antenna for a modern reciever with the antenna hookups I
desribed. and not too huge, maybe like 2 feet or so in diameter.
It
seems to me that most of the stuff I have read deals more with
the
construction of the frame and stuff, and less about the wiring
etc.
I
will have no problem figuring out a sutible frame design and
what I
was really looking for was a simple description of the correct
windings for a said diameter. Also I'm not sure how to hook it
up
to
the reciever, do I need this "coupling winding"? Or in my case
do I
just hook up the main windings to the antenna hookup on the
reciever.
Also, there is no variable resistor on the little plastic loop
that
came with the reciever, does this mean that I don't need one if
I
build my own?
I thank you for any comments/ suggestions that would help me
out. I
don't think I will be getting into this as a hobby or anything,
I
was
just hoping to make one that would get the station I want, which
is
570 AM, which has somwe interesting stuff on it at night, but it
would be cool if the loop worked through the whole band decently
also
as I thought it might be fun to surf the whole spectrum for some
cool
talk shows.
Thanx again in advance,
chris
