On Dec 31 2008, 4:10*pm, Roy Lewallen wrote:
Richard Fry wrote:
Roy Lewallen's post of Dec 29, 9:45 pm generally supports the points I
have been writing about.

That surprises me. Apparently I didn't understand your points, which
seem to emphasize the importance of considering the field very close to
the antenna in evaluating an antenna's performance for long-distance
skip communication. The data I posted show clearly that this isn't so,
because that strong field at low angles is attenuated to virtually zero
well before it can reach the ionosphere. The low elevation angle field
close to the antenna is of interest only if the other station is close
to the antenna.

If this belief were true then the long-distance coverage possible for
some MW broadcast stations would have to be made using more than a
single reflection from the ionosphere. Yet the texts of Terman
( http://i62.photobucket.com/albums/h8...ermanFig55.jpg ) and
Laport ( http://i62.photobucket.com/albums/h8...aportFig23.jpg
) show that such coverage is possible from single-hop skywave radiated
at elevation angles of just a few degrees.

And as this is true for MW broadcast monopoles, it is equally true for
the HF monopoles used by amateurs.

Sorry, I interpreted your postings to state that the surface wave was an
important factor to consider in determining the strength of the field
from a vertical for working skip communication. If that's not what you
meant, then exactly what is the point you were trying to make regarding
the importance of considering the surface wave for amateur communication?

Again, I do not, and never have considered the surface wave to be
important in skywave communications. The reason I referred to it was
to show that if it exists with substantial relative field close to the
radiator, then so does substantial radiation exist there at low
elevation angles, and which can serve the most distance ranges using a
single reflection from the ionosphere.

RF