[TowerTalk] Beverages and Trees
K7GCO@aol.com
K7GCO@aol.com
Wed, 8 Mar 2000 16:21:39 EST
In a message dated 08.03.00 10:13:58 Pacific Standard Time,
alsopb@gloryroad.net writes:
<<
"Just as it is not recommended to put up vertically polarized antennas
between tall trees, it is not a good idea to run a Beverage antenna
through the woods"
>>
This is particularly true with "Iron Wood" and "Silver Maple" Trees.
They have been know to act as "Log Periodic Reflectors and Directors. In W6
land, strange Forrest fires have started without lightning? I once showed a
Pine tree used a Circularly Polarized Log Periodic and feeding it just by
bending the 50 ohm limb down for a "Limb O. Match." Or you can just drive a
nail into the root system for a "Root Ground" already there and gamma
matching at the desired feedpoint Z with a series Xc made from a circular
strip of bark around the trunk of the right width and location. The bottom
limbs are usually 1/4 Wave Limb above the Root Ground to RF but not
electrostatically disconnect it from the Root Ground. It's a very quiet tree
for receiving.
I then saw in a W.W.II Radio Manual where they gamma matched a tree for an
emergency antenna and used fence wires for beverages.
There is a "Plant Stimulator" you can buy where you stick 2 nails in the pot
on each side of the main stem and pulsed it with square waves. I've had a
vertical in a tree for years and that tree has grown taller than the rest
over 45 years with "RF Stimulation". Regardless of the conductivity and
capacitive affect of the wire next to it, it's compensated for by the length
of the main wire. No Conflict. I couldn't run radials so I ran spikes into
the big roots. The coax was buried at night and bark colored insulated wire
went up the tree under the bark for the 1st 6'. The owner still doesn't know
it's there. It also had great bandwidth. I've also stashed 3 and 5 band
verticals in neighbors trees with the base about 30 feet off the ground. The
green radials were thrown over the limbs of the right length. There were
20,17,15,12&10M radial limbs right there. The coax was cut into the bark for
6' and the antenna was camouflage painted. It's called "Stealth Creative
Antenna Installing." Trees are great friends-even the neighbors at night. A
yagi in a tree is a tough installation as it gets wiggled a lot more. I did
have a tri-band dipole for a pick up antenna for beam pattern testing in the
top of a tree. The coax shield to the antenna on top was loaded as a top
loaded 1/2 wave on 80 with an L network grounded to the "Root Ground." The
matching system was just on my side of the property line. It worked great. I
had no way to install the equivalent without the tree.
Note! This is all absolutely true. I did not just make it up--maybe just a
small part. K7GCO
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