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Message-ID: <001101ce9428$e14548e0$0201a8c0@marco09cqcdi12>
From: "Marco Cadeddu" <marcocadeddu@tin.it>
To: <rsgb_lf_group@blacksheep.org>
References: <5202DE92.4040507@virginbroadband.com.au>
Date: Thu, 8 Aug 2013 11:17:33 -0000
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Subject: LF: Re: [OT] Quadrocopter antenna
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Status: O

Hi Edgar,

maybe after the retiring (but when??) I will come to visit the second part
of VK including Tasmania..
It is nice to see a lot of people doing (I mean really "doing") in these
times where most part of people prefere to criticize..
I just red your paper on your recent experience and wish to share with you
some thoughts.
Carbon is available in several physical forms whith different electrical
properties due to lattice configuration (think to diamond and grafite..)
some of these forms have a certain electrical conducibility.
Carbon fibers show electrical conducibility but in the final analisys are
resistance: I don't know if you tried to check with a multimeter the
resistance of the 1m carbon fiber strap, probably it is few ohms therefore
inserted in serie between the alu-whip and the FET amplifier (in high
impedance environment) it makes no difference.
Although light it is probably not suitable for a transmitting antenna: (what
about the resistance of 100 or more meters?) if the quadrucopter lift can be
carried out, probably an alu wire (see for istance welding wire) can be more
suitable for mechanical and electrical properties.
I'm a bit concerned about few things in the use of quadrucopters as
replacement of kites or ballons:
1: will the rx happy with high E field from the transmission? ok it works on
2,4 GHz, but you know all this modern small wonder boxes are not so rugged
and RF proof
2: batteries should last about 10-15 minutes, if I have to send IK1HSS in
DFCW qrss60 must transmit for 36 minutes this mens at least 3 batteries
(take off, tuning in place, transmission, sefe return) LiPo batteries are
very light but this is extra payload (batteries are rated for that time
lifting the quadrucopter and maybe the camera, I suppose that lifting the
antenna and the extra batteries will increase the power consumption
shortening the flight time)
3: power extension cord.. disregarding the load, and the possible troubles
in coupling/decoupling power specially at the top of antenna, what will the
antenna behaviour with a lined close to the antenna itself and with one end
probably connected to ground?

Beyond my concerns, my congrats in advance if somebody will try it!

73 de Marco IK1HSS
----- Original Message -----
From: "edgar" <edgarjtwining@virginbroadband.com.au>
To: <rsgb_lf_group@blacksheep.org>; <rsgb_lf_group@yahoogroups.co.uk>
Cc: <600m@yahoogroups.com>
Sent: Wednesday, August 07, 2013 11:56 PM
Subject: LF: [OT] Quadrocopter antenna


> Hi,
>
> A test was conducted to determine if Carbon Fibre could be used as part
> of the receiving element in an antenna.
>
> The results here.
>
> https://dl.dropboxusercontent.com/u/101251787/Carbon%20Fibre%20Whip.pdf
>
> Regards, Edgar
> Moonah, Tasmania.
>