RadioBanter - View Single Post - Hoola-Loop Antenna

May 8th 05, 09:49 PM

In article ,
wrote:

Just as a basic experament, I tried building a loop antenna out of a
hoola hoop.

I wrapped 4 turns of 24 gauge (cheap speaker wire) around a
hoola-hoop.

While the antenna "worked" it didn't have the directional properties
I had expected. It basically seemed as though it was just a plain
wire antenna.

Rotating it or placing magnetic materials inside of the loop seemed
to have little or no effect.

Could it be that I used electrical tape to hold the wires in place?
Could it be the curve of the tubing? (Unlike a very large diameter
cardboard tube or spool, with a flat surface, the wires aren't flat
they're on a curved surface (plastic tubing) making a circle. I hope
I'm explaining this right.

How does one determine the number of twists to use?

Anyone else try this with success?

The twisting the wire around the hoop will make the coil look less flat
than a one turn electrically similar to physically and this will make a
null less defined but that may not be the main problem.

The main problem may be the frequency you are trying to operate it at. A
loop null will work best when you have a transmitted source that looks
like a point source like daytime BCB or a ground wave signal. If you are
trying to use this hoop on short wave with reflected or refracted waves
off the ionosphere then the source is spread out and you won't get a
good null on a signal with the hoop. On the short wave band you can get
a null on a one turn loop at the low end. I've done it for 5 MHz WWV but
the higher you go in frequency the harder it gets. A small amplified
loop can probably do it at higher frequencies.

Another problem might be the way you terminated it as any antenna needs
to be terminated properly.

--
Telamon
Ventura, California