[TowerTalk] Tom, this article refers to a practiacl Vee Beam

[K0FF]

Before I retired, my wife and I lived in a subdivision with strict rules
about antennas. The rule was: NO ANTENNAS.
Frustrated by this, I decided to see what we could get away with. The
particular house we lived in was a two-story with a walkout basement,
leaving the eves of the back about 27 feet off the ground. Not great, but it
should be adequate to support some wire antennas.What evolved is a fan-Vee
antenna that covers 8 bands without a tuner, and 9 or 10 with one.

A wooden deck was attached at the first floor, so that the eves were
reachable via an extension ladder from there. First I put an screw-eye into
the eves, and ran a string through it. For days I played around trying
different types of twine and rope through the screw eye, and then walking to
the extreme of the lot to see if it could be seen or not. Finally a color of
heavy twine was found that matched the housepaint, and was for all practical
purposes invisible. Next was to find invisible wire for the antenna itself.
Very thin wire was pretty hard to see, but had a tendency to break. The
answer was electric fence wire. The thinnest possible version was obtained
from the hardware store, and it proved to be very strong, and eventually
weathered into a gray color that faded into the usually overcast sky of
St.Louis. The hardware to mount the connections to, and also the end
insulators
were fashioned from clear Plexiglas, and the guy lines were heavy
monofilament. All quite invisible.

The electrical design was challenging. I wanted as many bands as I could
get, with as few wires as possible. What evolved was a 6 wire fan that
covered 8 bands without a tuner, and 10 with a tuner. Two sets of 3 wires on
each side, in a sort of nested VEE. The 80/40 M vees were of conventional
design, and shared a common feedpoint (fed with housepainted disguised
coax!).
The other bands were covered by another Vee, this one being 122.5 feet on a
leg. The configuration is that of an "Unterminated VEE Beam" The antenna is
bi-directional in the direction it's pointing and is simply nested within
the innermost portion of the fan. Feeding is done with another coax via a
4:1 torroid balun, the one Amidon sells as a kit, and that covers 160M.
Let's consider  the length of the thing, and why it works without a tuner. A
VEE BEAM  can be any ODD multiple of a 1/2 wavelength, plus another 1/4
wavelength. This may seem to be an odd way to state it, but the extra 1/4
wavelength is there only to bring the feed impedance down to a lower level.
Trying to end feed a 1/2 wave can be disastrous.
Another way to look at is the antenna will work with 3/4, 5/4, 7/4, 9/4,
11/4, 13/4, 15/4, 17/4, 19/4, 21/4, 23/4 and 25/4 waves long. To do the math
remember that there is only one "end" so there will be only one "end
effect" to deal with. This results in one of the 1/4 waves figured as 234/f
while all the others go at 251/f.
On 160 Meters the thing is pretty close to a 1/4 wave, and acts as a high
angle radiator, being good for stateside contacts.  At 30M the antenna acts
like 5 quarterwaves almost exactly. For 20M we see 7/4 and this thing works
like gangbusters there! 17M is 9/4 and 15M is more or less 11/4 but will
probably need a tuner (close enough that the autotuner in the rig should
work
fine). 12 meters is the orphan and the antenna sees no real relationship
here, but it can be used as a random wire with a good tuner.10M is 15/4 at
28.5MHz.
25/4 falls in the 6 meter band.
Tuning up any multiband radiator is a labor of love and this one is no
exception. The VEE-Beam portion requires no pruning, but the angles both
included, and vertical, can be optimized for best results. The 40/80  combo
is made a little more difficult because of their common feed point, but
again by adjusting their angles, and trying to keep their ends as far apart
as practical it can be done.

To make the connections at the feedpoint, I took a piece of 1/4 in thick
clear Plexiglas 9" long and 2" wide, and drilled one hole in the middle of
the long dimension 1/2" back from the edge. The twine attaches here, and
goes up through the eyehook. On the opposite edge, I drilled 8 more 1/4"
holes also 1/2" back from the edge, 4 on each side of center and balanced
with a space in the middle between the two sets of 4. Into each of these 8
holes went a S.S. 1/4-20 bolt 1" long, and tightened down with a flatwasher
on each side, then a lockwasher and not. Above that nut goes two more flat
washers and a wingnut. All the wires attach under the wingnut/washer.

On the two middle bolts goes the 122.5' wires and the terminals from the 4:1
Balun. It hangs down and the coax goes to the connector on it. Next pair out
goes the coax for the 80/40, and a jumper wire 3" long. Between the outside
2 bolts on each side, connect a coil. Airdux type - 1-1/4" diameter and 8
turns. Put this on the bolthead side, s it will remain here, and you don't
want it to slip off during adjustment.Now on the outside bolt, under the
nut (not wingnut) goes the 80/40 wires.

Now, put the 3" jumper's free end under the wingnut of the far outside bolt.
This hooks the coax directly to the wires, and the coil is not in the
circuit. Hoist the feedblock all the way up to the eyebolt, and proceed to
adjust the  80/40 antennas in their respective SSB portions of the band.
Once this is done, and you then want to go on CW, esp on 80M, you lower the
feedblock back down and move the jumper in one bolt, so that the coil is now
in series, lowering the frequency of resonance just enough to cove the CW
portion. A naturally resonant center fed 1/2 wave antenna has as broad a
frequency curve as any antenna can have, and on 40 at least, you may already
be able to cover the whole band without switching in the coil.





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