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Old April 19th 15, 08:00 PM posted to rec.radio.amateur.antenna
Ian Jackson[_2_] Ian Jackson[_2_] is offline
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First recorded activity by RadioBanter: Nov 2007
Posts: 568
Default A Top Band 1/4 wave vertical?

In message , Jeff Liebermann
writes
On 19 Apr 2015 10:45:10 GMT, Rob wrote:

But do you want a radio controlled gadget with 4 electric motors at
the top end of your vertical?


A drone would work, but does not have enough battery capacity to be
able to keep the antenna in place for more than about 10-20 mins.
Longer would require seperate power wires, which would interfere with
the radiation pattern.

Weight might be a problem. I'll guess(tm) #16 AWG wire, which weighs
7.82 lbs/1000ft or 11.6 gm/meter. 1/4 wave at 160 meters is 40 meters
so that antenna would weigh:
11.6 gm/meter * 40 = 464 gm
Hmmm... Probably too heavy. By comparison, a GoPro camera body weighs
100 gm. Ok, smaller guage wire or bigger quadcopter.

16AWG wire does indeed seem a bit overkill (at least for the sort of
powers that UK amateurs are allowed to run). Something much thinner and
lighter would do (eg PVC covered multistrand flex).

With a little ingenuity, there's no reason why you couldn't feed DC
'line power' up the antenna wires (or, more accurately RF up the power
wires).

If there's any danger of the pull of the copter snapping the wires, it
could be restrained with (say) thin woven nylon cord.

However, how would the intricate control circuitry in the copter cope
with the very high level of RF signal?








--
Ian