RE:
>> Those fields from very low elevation angles (say, less then 5 degrees)
>> can reach the ionosphere, and under the right conditions return to the
>> earth as a useful skywave.
Mike Waters asks:
>My question is, on what amateur bands is this common? And on what
>amateur bands is this possible?
It is universally common for the highest radiated fields launched by
vertical monopoles to occur in the elevation sector between the horizontal
plane and 5 degrees above the horizontal plane. This is a natural
consequence of the summation of individual fields generated along the height
of the monopole by the r-f current flow there.
The graphic linked below is taken from Radio Engineers' Handbook by F. E.
Terman (1st Ed), showing that the skywave from the monopole of a typical AM
broadcast station that serves the greatest single-hop range leaves the
radiator at elevation angles of 5 degrees and less.
This will be true for HF monopoles, also, but the range would depend on the
height of the layer of the ionosphere where the reflection takes place.
http://i62.photobucket.com/albums/h85/rfry-100/TermanFig55.jpg
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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