Dear John:
If you were a radio amateur who is interested in working other radio
amateurs at a great distance, then you wish to have a significant portion of
your antenna's radiation within about 12 to 2 degrees above the horizon.

In tern, this goal suggests that a preferred height for an HF,
horizontally-polarized antenna is between 2 and 2.5 wavelengths above
ground.

If the higher angle radiation does not pass through the ionosphere, it
contributes to interference to (relatively) nearby stations (and, because
the antenna probably is used for reception, contributes to hearing nearby
stations). Expensive HF antenna systems exist that significantly suppress
all except the lowest lobe.

If you wish to be a student of antennas, do invest in Kraus' 3rd edition
of Antennas. Read and study the book starting with the first chapter.

Regards, Mac N8TT


--
J. Mc Laughlin; Michigan U.S.A.
Home:
"jawod" wrote in message
...
Tried to make the subject grab a bit.

I just fininshed the ARRL Antenna Book Chapter on Effects of Ground.
There are HFTA graphs showing elevation response for various antenna
configurations (mostly Yagis).

Most arrays show good response up to 12 degrees above the horizon, then
many show a null and then, a second peak around 25 to 30 degrees above
the horizon.

Here's my question:
At 25 to 30 degrees elevation response, aren't these waves leaving the
ionosphere (i.e., refracted instead of reflected)?

Am I right to consider this component of propagation to have left the
earth?

This would indicate a substantial fraction of each amateur transmission
is sent into space.

I always thought Broadcast transmissions were most likely to emanate
from Earth. Are hams more or less likely to transmit into space than
Broadcast?

John
(who wishes to remain a student and never an expert)