Ron Wanttaja wrote:

the antenna can be just a bit of wire.

the trick is to cut it to the right length.

Might I suggest a "marconi antenna"? Do a google on it,
it's just a vertical piece of wire, cut to 1/4 wavelength,
with a horizontal ground plane underneath.

What's 1/4 wavelength? Well, from high school physics we
fundamentally we know that

V = F * Lambda

Where V = velocity, F = frequency, Lambda = wavelength

Using grade 8 algebra, divide both sides of the equation
by (non-zero) F to isolate Lambda gives:

Lambda = V / F

Assuming that radio waves move at the speed of light,
We know that V = 3 x 10^8 meters per second, and let's
use a nominal F = 120 Mhz or 120 x 10^6 = 1.2 x 10^8

Therefore Lamda = 3 / 1.2 = 2.5 meters. Therefore
1/4 wavelength would be 0.625 meters or around 24.4 inches.

Keep in mind, though, I'm just a dumb airshow pilot -
check with Jim about this. He builds these in his sleep
from welding rod.

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ATP http://www.pittspecials.com/images/oz_inv.jpg