On Sun, 22 Jul 2007 08:41:15 -0700 (PDT), R. David Eagle wrote:
>Is there a huge difference in efficiency between 40 and 60 feet?
In general, the vertical portion of the antenna provides the
vertically polarized component of radiation, and is more lower
angle radiation. The horizontal portion radiates horizontally
polarized, and at a higher angle.
Another form of antenna closely related to the inv L is the Tee,
which has wire on both sides of the top of the vertical. That
antenna tends to have ONLY vertical radiation, which is better if
you want to work DX.
>I will stay away from the elevated radials debate.
Science is not a matter of debate, but of facts, carefully proven.
There's a lot of science that shows that elevated radials work
fine -- IF they are actually elevated. In general, radials don't
behave as elevated until they're at least 1/8 wavelength above the
earth. The closer they are to the earth, the more they act like
they were actually on the ground (that is, you need a lot of
them). The more they're elevated, the more they act like elevated
radials (that is, you don't need very many of them). By "work
fine" I mean that they provide a low resistance (low loss) path
for antenna return current. By not work fine, I mean that they
couple in a lot of loss from the earth, which wastes transmitter
power (and makes your signal weaker by that numbe of dB).
73,
Jim Brown K9YC
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