Ideally (and this may be too many wires to be practical) I would like
to construct an 80/60/40/30 meter fan dipole requiring only a single
rope at each end. Major project is OK if the end result is viable.
I would not recommend a parallel/fan dipole with 80/30 meters. I've
tried it several times and the 80 meters wire detunes 30 meters. The
antenna works as badly as if one simply used a tuner to force power
into the 80 meter wire.
*IF* I were going to try an 80/60/40/30 combination, I would get two
sets of traps (Reyco KW40 and KW30) and build a fan of trapped
antennas. One antenna would be 80/30 meters (the traps isolating
the 30 and 80 sections) the other would be 60/40 meters. However, I
am not comfortable with the behavior of 60 and 80 meters in parallel.
The better "solution" for fan dipoles would be two fans - one for
80/40 and one for 60/30 where one has a harmonic relationship between
the two bands in the antenna.
Parallel/Fan dipoles work because the lower band antennas represent
a *high impedance* across the feed point of the active band antenna.
When one has a fan in which the bands are not harmonically related,
that high impedance relationship is upset and the "inactive" wires
now present significant inductance/capacitance in parallel with the
feed point.
73,
... Joe, W4TV
On 10/1/2017 7:21 AM, N1BUG wrote:
I've been reading the fan dipole discussion with much interest. I have
used fan dipoles for many years, as inverted V, common center point with
the ends tied off separately. The biggest one (a club project) had 6
wires for 160/80/40/20/15/10. It worked OK but that was a lot of rope!
Currently I have individual inverted V antennas for each of several
bands all supported from various points on one tower. I would like to
reduce the number or ropes tied off everywhere.
If you have successfully constructed and used a fan dipole where one or
more more wires hang from the first and each end requires only a single
support rope I would like to see details of the construction. I have
made a few attempts and seen some others but they all either suffered
from the lower wires sagging, constantly breaking spreaders or both.
Ideally (and this may be too many wires to be practical) I would like to
construct an 80/60/40/30 meter fan dipole requiring only a single rope
at each end. Major project is OK if the end result is viable.
73,
Paul N1BUG
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