On Wed, 24 Dec 2008 10:57:12 -0600
"Kevin Schavee" <n0cwrham@gmail.com> wrote:
> Has any one modeled the difference between Inverted L
>and full size
> 1/4 wave 160m antennas?
Kevin,
I have and used both recently. I have at home a vertical
and used an Inverted L on 5K0T just a few weeks ago.
Modeling Results:
Inv L: 18m Vert, 24m hor: 1.2 dBi average, Best Dir 1.8
dBi, Worst Dir .6 dBi.
Vert: 40.5m Vert: 1.6 dBi.
Notes: Wire: Copper, vertical wire 2 mm dia, horizontal
wire 1 mm dia (on Inv L), Radials: 6 x 20 m long, 1 mm
dia, copper, on ground. Ground: Average, 5 mS conductivity
and a Dielectric Constant of 13. I modeled a minimum
radial system as this is where the difference is the most
pronounced. Note that there are many other combinations of
conductors, ground and radials that will all yield
different modeling results.
From a practical stand-point, the difference is not big
(1dB). So it all depends on the supports you have: if you
can support a 40 meter tall vertical radiator, by all
means this is the better antenna. On the other hand, if
all you can have is an inverted L, do not despair, it has
the potential to be a good DX antenna. The ground system
can make a much larger difference than the difference
between the two antenna types, and is far more worth
investing in. If your antenna is not a great performer,
look at the ground and radial system first!
73,
George
AA7JV
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