Have you ever seen the movie "Contact" s ? Radio waves that are not
reflected and ultimately attenuated into nothingness by the atmosphere (the
electromagnetic radiation becomes heat) end up travelling through space
forever . My answer is, the higher the better. Consider that some waves get
caught in a "conduit" in the atmosphere and flow around the globe. That can
be thousands of feet up. If you have a conductor in the air that gets hit by
an electromagnetic wave, it will travel to your receiver if connected S.
On the other hand, if you have a storm in the area, at least disconnect that
wire LOL. You would need to be tuned to the right frequency of course unless
the signal is so broadband (lightening for instance) that it impacts a large
band of frequencies. Spark gaps are famous for radiating energy in a strong
signal all up and down the shortwave bands.

Ultimately, the wire could be many miles long. The levels of the atmosphere
ionised can be miles up. That accounts for why some signals are audible at
one time in the day and not during other times. The atmosphere is ionised
and coalesces into layers during the day and the layers later dissipate.
Radio signals are bent by the ionised layers and emerge from the layers at
various angles. The signal may bounce over long distances or short depending
on how high the layer is. It is a matter of the angle at which the signal
encounters the layer.

The behavior of charged particles can be a lot like magnets. As it happens,
charged particles behave predictably in the presence of magnetic fields. A
magnetic field will distribute particles charged one way or another.
Negatively charged particles go one direction, and positively charged
particles go another. If the magnetic field in an environment is strong
enough, it wreak havoc on a wave. The magnetic field of the earth is getting
weaker, and it may soon be the case, that there is more than one magnetic
north pole, and one magnetic south pole. This makes shortwave reception a
whole new ballgame.


All life all holiness come from you O Lord
wrote in message
...
How far up in the air can a wire antenna for shortwave radio be (for
instance,held aloft with a helium balloon,ala Switzerland in World War
Two) and still be effective for receiving shortwave radio signals?
cuhulin