Looking at portable and easy to deploy method of putting up a 5/8 omni
directional antenna for CB/10-11m trans/rec. Is hooking up an antenna
wire to a helium balloon on the "top" end and connecting it to coax at
the "bottom" a possible option? Obviously there are many
environmental limitations with the concept, and it is a strictly
single use application. But for camping or emergency back up use, the
concept sounds at least plausible. Anyone have any technical reasons
why this is not feasible? Better yet, anyone have any experience with
anything similar?

"MLNJ" wrote in message
...
Looking at portable and easy to deploy method of putting up a 5/8 omni
directional antenna for CB/10-11m trans/rec. Is hooking up an antenna
wire to a helium balloon on the "top" end and connecting it to coax at
the "bottom" a possible option? Obviously there are many
environmental limitations with the concept, and it is a strictly
single use application. But for camping or emergency back up use, the
concept sounds at least plausible. Anyone have any technical reasons
why this is not feasible? Better yet, anyone have any experience with
anything similar?

If you include operation in the rain then the balloon needs to be attached
to a low-voltage point on the antenna - certainly not the end of a dipole
element because a wet string leading to a wet balloon would likely detune
it. Some people I used to know used discones in this application, and the
centre of the disc is a relatively low-voltage/low-impedance part of the
antenna. The technique was used extensively in planning the UHF transmitter
network for television broadcasting in the UK, before computer modelling and
simulation was allowed to take over with remarkably little proof of its
accuracy!

Chris

El 25-03-12 23:22, MLNJ escribió:
Looking at portable and easy to deploy method of putting up a 5/8 omni
directional antenna for CB/10-11m trans/rec. Is hooking up an antenna
wire to a helium balloon on the "top" end and connecting it to coax at
the "bottom" a possible option? Obviously there are many
environmental limitations with the concept, and it is a strictly
single use application. But for camping or emergency back up use, the
concept sounds at least plausible. Anyone have any technical reasons
why this is not feasible? Better yet, anyone have any experience with
anything similar?

I would not use a 5/8 antenna, as this requires 1/4 lambda radials,
and has (virtually) no advantage over a half wave. A half wave wire
end-fed antenna design can be used without radials mostly.

If you use grease impregnated wire, or monofilament line to tie the
antenna to the balloon, it will not reduce efficiency, even under wet
conditions. Of course you could also use a plastic insulator. you may
know raising the antenna will enhance ground wave propagation, but
above a certain height will not improve ionospheric propagation.

Why not use a fiberglass mast?


--
Wim
PA3DJS
www.tetech.nl
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