Hello All,
I am about to undertake an antenna upgrade for my club
station. 1 important element has yet to be figured out: What, if any
antenna we can have for the top band. Let me describe the
situation. We are a University Club station.. All of the antennas,
Towers, Etc. need to be on the roof, In a space about 100 X 75 Ft.
We currently have 2 towers, Both Rohn 25 at 40 ft each, On
opposite sides of the roof. Tower #1 Has all the Repeater Antennas
and Vhf/Uhf Gear.. Tower #2 Is HF and holds the 2 tribanders (Th-6
at 45, A-4 At 15). The VHF tower has insulated guy wires, The HF
Tower is not guyed. We currently have a 40/80 Fan Dipole running
between both towers, With the 40 meter wire running straight
across to both, the 80 of at a 45 degree angle. (Below is Supposed
to be a rectangular box btw.. Forgive the artwork...)
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| X VHF | Each Long Side 100 Ft
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<--- | | (Not To Scale)
NE | |
EU) | |
| | ^^^ = Entry Structure
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| X HF |
| ^^^^ |
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Each Short Side 75 Ft
Now, what antenna can we fit up there? No room for a dipole.
We tried a sloper but ended up bending it around a few corners and
was pretty much deaf on receive and transmit, being 1 ft off the
ground for alot of its run. An inverted L would be next to impossible
to set up, Let alone in a useful direction, Considering the wires
already running around up there.. So that leaves me with 1 thought,
Unless someone can help out with a another suggestion: Shunt
Feeding the Towers.
Now i know they are both a bit short, But with the 2 Beams on
the HF tower, Im thinking it might work. But there is no real
ground per say up there.. The only ground is the piece of
grounding braid, Thats attached to the tower; Part of the roofs
lightning protection. Runs around the roof, To drop points, Where
the braid runs 50 ft down to the ground, then to rods that go down
another 50 ft.
My question is, Is there hope of shunt feeding the towers? I am
ewbie when it comes to top band antennas, so any and all help
will be appreciated. Any websites and such on the subject matter
would be helpful.. Thanks in advance for the help.Much appreciated
by this station...
Ulysses Rodriguez - KD4RWN
President - University Of Central Florida ARC (K4UCF)
Member: ARRL, FCG, WWYC # 77
kd4rwn@arrl.net
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