Spike wrote:
On 07/03/15 01:49, wrote:
In rec.radio.amateur.antenna Spike wrote:

Imagine a short rod vertical aerial not connected to ground, for the
(say) 160/80/60/40m bands, as might be found in a typical /M set-up, fed
with RF energy and operating over ground of average conductivity.

Three different waves will be launched from this: the sky wave, the
space wave (including the reflected ray), and the surface wave. Each of
these have their own characteristics, inasmuch as the sky wave is
launched willy-nilly even if the band isn't open for that mode, the
space wave depends on the path to the receiver, and the surface wave
depends on the electromagnetic characteristics of the air and the
surface material, although to some extent the latter affects all the
waves generated.

These "waves" are actually called skywave and surface wave and are
a propagation phenomena.

See:

http://en.wikipedia.org/wiki/Skywave
http://en.wikipedia.org/wiki/Surface_wave
http://en.wikipedia.org/wiki/Line-of-sight_propagation

for how signals propagate.

Thanks to you and Jerry Stuckle for your replies.

Since a vertical aerial that I described initially emits all three of
these waves, I was interested in the relative amounts of the RF power
supplied to the antenna that goes into each. For example, does the sky
wave component take 90% of the power, leaving 10% for the space and
surface waves? What phenomena control this?


You've totally missed the point.

These "wave" phenomena are determined by the frequency and the condition
of the ionosphere, which is influenced by solar radiation.

A transmitting antenna knows nothing about any type of propagation.

The amount of any type of "wave" propagation that will happen depneds
on the antenna pattern, i.e. how much energy is radiated in any particular
direction, and the current ionospheric conditions.

There is a rule of thumb that says that maximum skywave occurs at an
antenna main lobe elevation of about 30 degrees, but it is only a
general rule of thumb. The exact angle will be determined by the
frequency and current condition of the ionosphere.



--
Jim Pennino