Mike Morrow <[EMAIL PROTECTED]> wrote on Thursday, April 17, 2008 9:12 PM
One can make contacts with even the poorest of antennas, and not realize
how
poor the performance is. Side-by-side tests out in the boonies is the
real
test of relative performance. Nothing beats that!
----------------------------------------------------------
Absolutely! For a number of years at this rural location I used full sized
vertical dipoles for 40m in phased arrays and as omnidirectional antennas,
with their top ends at approximately 70ft. It became painfully obvious
after a while that in their favoured directions these vertical antennas
performed better on DX paths when firing across open farm fields than when
firing through nearby large trees, such as oak, when their sap was running
i.e Spring through Fall. As an example the long path to Japan is roughly
16600 miles from here across open fields, the short path roughly 4900 miles
through nearby trees, and the long path across the fields into JA was always
'easier' to work than the short path when using the verticals.
So I put up a horizontal 40m dipole at 70ft which also fires towards Japan.
Not only did the tree problem appear to disappear, but also the dipole's
better performance at low angles compared with that of the vertical antennas
found from side-by-side tests, made on 40m over a long period, was very
apparent on both the short and long paths into Japan. The penalty is that
the low angle nulls off the ends of a horizontal dipole at this height are
very noticeable on long distance paths when the angle of arrival is low.
73,
Geoff
GM4ESD
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