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Date: Tue, 06 Aug 2013 18:25:33 +0200
From: DK1IS <DK1IS@kabelmail.de>
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Subject: Re: LF: Quadrocopter antenna
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Hello group,

nice stuff and very exciting, but against my background of arcs and=20
sparks I would recommend to consider the following before making tests=20
with quadrocopter carried antennas:

1.  Every conductor being intentionally in a high voltage field has to=20
have a well-defined electric potential. If you use direct DC feeding of=20
the quadro this happens self-acting, if you use an inverter at the=20
skyside end you have to make a galvanic connection between the feeder=20
line and the quadro electronics.
2.  Assuming the quadro to be a sphere in free space with a diameter of=20
1 m it would have a capacity of about 56 pF against ground. Feeding it=20
with 10 kV at 136 kHz this would result in a current of 480 mA emanating=20
from the conducting parts of the quadro. This impressed current wouldn=C2=
=B4t=20
care about any pn-junction on its way - not at all a healthy situation=20
for the quadro=C2=B4s electronics (the 1945 3-phase-AC motor heli would h=
ave=20
laughed at this challenge!).
3.  To overcome this problem it would be useful to install some field=20
shaping items which reduce the voltage gradient around the quadro. At=20
its best this could be a wide meshed cage around the quadro from light=20
conducting material being connected to the quadro=C2=B4s electronic groun=
d,=20
e.g. aluminum wire (welding wire) or balsa wood with a coat from=20
aluminum foil, self adhesive like that used for repairing roofs. Of=20
course this cage shouldn=C2=B4t disturb the aerodynamic properties of the=
=20
quadro. The second best solution (a little bit theoretical?) could be to=20
make two wide meshed ellipsoids (as a limit case spoke wheels), diameter=20
exceeding that of the quadro if possible, one piece being mounted upside=20
of the quadro, the other piece one to three meters downside at the=20
feedline, both connected to the feedline resp. quadro=C2=B4s electronic=20
ground. Mounting has to be so that wind and vibration won=C2=B4t tilt ove=
r=20
these electodes to the quadro rotors ...
As a minimal solution as much as possible of the quadro=C2=B4s surface sh=
ould=20
be coated with self adhesive aluminum foil connected to electronic=20
ground to give root points for the lines of electric flux outside the=20
vulnerable parts.
4.  Having done this, during start keep in mind the galvanic connection=20
to the feedline ;-)
5.  There should be a DC path from the antenna system to ground to bleed=20
off electrostatic charges.
6.  Let=C2=B4s pray that the brushless motors of the quadro don=C2=B4t wo=
rk on=20
your favourite QRG - the effect would be disastrous both at TXing and=20
RXing ... For the latter you should take an conventional loop and detune=20
the TX ant anyway.

After this marginal modifications your quadro will hopefully be still=20
going strong;-)!

73,
Tom, DK1IS

Am 06.08.2013 14:37, schrieb Markus Vester:
> Hi Stefan, LF,
> the quadrocopter which we tried was a DJI Phantom. It is smaller than=20
> the F550 and currently goes for around 570 Euro (ready to fly,=20
> including battery and a 2.4 GHz remote control). A similarly equipped=20
> model, Blade 350QX, should become available soon for about 450 Euro.=20
> Very light quadrocopters can be had for as little as 60 Euro but they=20
> could presumably lift only short and very thin wires.
> With GPS, gyro and compass sensors, the Phantom was indeed extremely=20
> easy to fly even by an unexperienced person like me. With 11.8V 2.2Ah=20
> LiPo battery it will stay aloft for 10 to 15 minutes, so power=20
> consumption must be around 120 W. The motors are said to be able to=20
> stand continuous duty. Lifting capability should be around 0.3 kg, and=20
> my friend intends to install a first-person-view video cam later. We=20
> have not tried to lift a wire or string yet, so I don't know how much=20
> the behaviour would be affected eg. by wind drag on the wire. With 6=20
> m/s climb rate, the heli could theoretically go up to 2000m and more=20
> on a battery charge. The remote control is specified for 300m range,=20
> which could probably be fixed by a higher gain 2.4 GHz transmit antenna.
> Yes power could be fed continuously by making the LF antenna a twin=20
> wire. On the ground either an Austen transformer or a bifilar wound=20
> loading coil could be used (maybe by splitting up groups of strands in=20
> the RF litz). The heli then cannot be separated by a distance from the=20
> antenna tip which may aggravate potential EMC issues. Alternatively, I=20
> am still wondering whether enough charging power could be extracted by=20
> capacitive coupling to the LF transmission...
> Currently in Germany there seem to be no general restrictions about=20
> flying light helis (less than 2 kg) even over inhabited terrain. I am=20
> not sure though about legal implications of a tethering wire or going=20
> to higher altitudes. Basic liability insurance seems definitely=20
> recommended and can be obtained eg by joining a model flight club.=20
> While hovering over houses after sunset with bright green and LED bars=20
> on, we were confronted by one neighbour who strongly expressed her=20
> dislike of the activity. People mostly seem to be concerned of=20
> "Papparazzi drones" invading their precious privacy, the acoustic=20
> noise when flying low, and surely the fear that these things might end=20
> up falling onto their heads.
> Best 73,
> Markus (DF6NM)
>
> -----Urspr=C3=BCngliche Mitteilung-----
> Von: Stefan Sch=C3=A4fer <Stefan.Schaefer@iup.uni-heidelberg.de>
> An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
> Verschickt: Di, 6 Aug 2013 1:43 am
> Betreff: Re: LF: Quadrocopter antenna, sri, a bit OT
>
> Hi Warren, LF/VLF,
>
> I just found this: http://www.youtube.com/watch?v=3DG3yR-GxD1is Take a=20
> look at it. I can't find the words. I think i must have one :-)
> That must be _SEVERAL_ 100m above ground. I think we could even do VLF=20
> experiments with such a copter. Maybe a 500m vertical? I remember the=20
> weight of the wire in my 300m kite antenna test was about 1.5 kg, not=20
> more. So with 500m we could come lower than 5.17 kHz, like i did in=20
> 2010/2011.
>
> 73, Stefan/DK7FC
>
>
> Am 06.08.2013 01:02, schrieb Warren Ziegler:
>> Stefan,
>>     But 100m is not better than your kite experiments!
>> Yes you gain control but not height.
>> You will still need a battery to land the quadcopter in the event of=20
>> a failure of the power carrying wire.
>>
>>
>> 73 W
>>
>>
>> On Mon, Aug 5, 2013 at 6:53 PM, Stefan Sch=C3=A4fer=20
>> <Stefan.Schaefer@iup.uni-heidelberg.de=20
>> <mailto:Stefan.Schaefer@iup.uni-heidelberg.de>> wrote:
>>
>>     Hi all,
>>
>>     I just gathered some informations from the web. Just one example
>>     for a, probably, suitable hexacopter to carry a LF transmit antenn=
a.
>>
>>     For example a DJI F550, see a video at
>>     http://www.youtube.com/watch?v=3DveDrtdE6njo or
>>     http://www.youtube.com/watch?v=3D2QC9so2so3Y). Looks like they can
>>     easily lift 1 kg! You can fly about 10 minutes with a 5.3 Ah
>>     battery. The battery voltage is to 11.1V...14.8V. So the power
>>     consumption may be 200...300 W ! With a compact SMPS on the
>>     copter and a 2 wire line it could be possible to carry the
>>     antenna. And 100m is no problem too!!
>>     I consider to buy one! And look this, most fascinating.
>>     http://www.youtube.com/watch?v=3DJecyY79K7kY
>>
>>     73, Stefan/DK7FC
>>
>>
>>     Am 05.08.2013 15:25, schrieb Stefan Sch=C3=A4fer:
>>>
>>>     Am 04.08.2013 17:52, schrieb DK1IS:
>>>>     [...]But with nowadays quadrocopters and a "little" reduction
>>>>     of the demands it should be possible to feed them from the
>>>>     ground with DC (or AC plus converters for reduction of current)
>>>>     via 2 wire line and having a good antenna too.
>>>>
>>>>     73,
>>>>     Tom, DK1IS
>>>
>>>     That's it! So, Markus, could you ask your friend abot some
>>>     technical details? What is the supply voltage of the system and
>>>     power consumption (or lifetime at a certain battery charge)? Is
>>>     it possible to lift 1 kg and how does it change the power
>>>     consumption? It should be no problem to feed DC to the system or
>>>     a compact power supply in the sky and normal 230V mains at
>>>     ground (todays PSUs have an input voltage range of 85...240V AC,
>>>     so a certain voltage drop on the thin wire should be no problem.
>>>     Maybe you can do some tests?
>>>
>>>     The advatages are clear. A quadrocopter keeps the position and
>>>     height, even in smaller wind blasts while a balloon bounces left
>>>     and right. The costs of Helium will quickly overcome the costs
>>>     for a quadrocopter. Ah and such a project is simply more
>>>     interesting i guess :-)
>>>
>>>     73, Stefan/DK7FC
>>
>>
>>
>>
>> --=20
>> 73 Warren K2ORS
>>                 WD2XGJ
>>                 WD2XSH/23
>>                 WE2XEB/2
>>                 WE2XGR/1
>>
>> Re: LF: USA issued 68 to 76 kHz band with 10 W ERP
>> Von: Markus Vester <markusvester@aol.com <mailto:markusvester@aol.com>=
>
>> An: rsgb_lf_group <rsgb_lf_group@blacksheep.org=20
>> <mailto:rsgb_lf_group@blacksheep.org>>
>> Datum: So, 4 Aug 2013 9:47 am
>> ...Yesterday night a friend showed me his new GPS-stabilized=20
>> quadrocopter. It's stunning how it could just about be parked in=20
>> midair, despite some lateral winds. Seems that would make a great=20
>> antenna carrier! Not all of the neighbour's seemed to enjoy it as=20
>> much as we did...
>>
>> Best 73,
>> Markus (DF6NM)


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pe">
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    <div class=3D"moz-cite-prefix">Hello group,<br>
      <br>
      nice stuff and very exciting, but against my background of arcs
      and sparks I would recommend to consider the following before
      making tests with quadrocopter carried antennas:<br>
      <br>
      1.=C2=A0 Every conductor being intentionally in a high voltage fiel=
d
      has to have a well-defined electric potential. If you use direct
      DC feeding of the quadro this happens self-acting, if you use an
      inverter at the skyside end you have to make a galvanic connection
      between the feeder line and the quadro electronics.<br>
      2.=C2=A0 Assuming the quadro to be a sphere in free space with a
      diameter of 1 m it would have a capacity of about 56 pF against
      ground. Feeding it with 10 kV at 136 kHz this would result in a=C2=A0
      current of 480 mA emanating from the conducting parts of the
      quadro. This impressed current wouldn=C2=B4t care about any pn-junc=
tion
      on its way - not at all a healthy situation for the quadro=C2=B4s
      electronics (the 1945 3-phase-AC motor heli would have laughed at
      this challenge!). <br>
      3.=C2=A0 To overcome this problem it would be useful to install som=
e
      field shaping items which reduce the voltage gradient around the
      quadro. At its best this could be a wide meshed cage around the
      quadro from light conducting material being connected to the
      quadro=C2=B4s electronic ground, e.g. aluminum wire (welding wire) =
or
      balsa wood with a coat from aluminum foil, self adhesive like that
      used for repairing roofs. Of course this cage shouldn=C2=B4t distur=
b
      the aerodynamic properties of the quadro. The second best solution
      (a little bit theoretical?) could be to make two wide meshed
      ellipsoids (as a limit case spoke wheels), diameter exceeding that
      of the quadro if possible, one piece being mounted upside of the
      quadro, the other piece one to three meters downside at the
      feedline, both connected to the feedline resp. quadro=C2=B4s electr=
onic
      ground. Mounting has to be so that wind and vibration won=C2=B4t ti=
lt
      over these electodes to the quadro rotors ... <br>
      As a minimal solution as much as possible of the quadro=C2=B4s surf=
ace
      should be coated with self adhesive aluminum foil connected to
      electronic ground to give root points for the lines of electric
      flux outside the vulnerable parts.<br>
      4.=C2=A0 Having done this, during start keep in mind the galvanic
      connection to the feedline ;-)<br>
      5.=C2=A0 There should be a DC path from the antenna system to groun=
d to
      bleed off electrostatic charges.<br>
      6.=C2=A0 Let=C2=B4s pray that the brushless motors of the quadro do=
n=C2=B4t work
      on your favourite QRG - the effect would be disastrous both at
      TXing and RXing ... For the latter you should take an conventional
      loop and detune the TX ant anyway.<br>
      <br>
      After this marginal modifications your quadro will hopefully be
      still going strong;-)!<br>
      <br>
      73,<br>
      Tom, DK1IS<br>
      <br>
      Am 06.08.2013 14:37, schrieb Markus Vester:<br>
    </div>
    <blockquote
      cite=3D"mid:8D060B8C892D2CF-2024-995@webmail-m221.sysops.aol.com"
      type=3D"cite">
      <div style=3D"FONT-FAMILY: arial; COLOR: black; FONT-SIZE: 10pt">Hi
        Stefan, LF,</div>
      <div>=C2=A0</div>
      <div>the quadrocopter which we tried was a DJI Phantom. It is
        smaller than the F550 and currently goes for around 570 Euro
        (ready to fly, including battery and a 2.4 GHz remote control).
        A similarly equipped model, Blade 350QX, should become available
        soon for about 450 Euro. Very light quadrocopters can be had for
        as little as 60 Euro but they could presumably lift only short
        and very thin wires.</div>
      <div>=C2=A0</div>
      <div>With GPS, gyro and compass sensors, the Phantom was indeed
        extremely easy to fly even by an unexperienced person like me.
        With 11.8V 2.2Ah LiPo battery it will stay aloft for 10 to 15
        minutes, so power consumption must be around 120 W. The motors
        are said to be able to stand continuous duty. Lifting capability
        should be around 0.3 kg, and my friend intends to install a
        first-person-view video cam later. We have not tried to lift a
        wire or string yet, so I don't know how much the behaviour would
        be affected eg. by wind drag on the wire.=C2=A0With 6 m/s climb r=
ate,
        the heli could theoretically go up to 2000m and more on a
        battery charge. The remote control is specified for 300m range,
        which could probably be fixed by a higher gain 2.4 GHz transmit
        antenna. </div>
      <div>=C2=A0</div>
      <div>Yes power could be fed continuously by making the LF antenna
        a twin wire. On the ground either an Austen transformer or a
        bifilar wound loading coil could be used (maybe by splitting up
        groups of strands in the RF litz). The heli then cannot be
        separated by a distance from the antenna tip which may aggravate
        potential EMC issues. Alternatively, I am still wondering
        whether enough charging power could be extracted by capacitive
        coupling to the LF transmission...</div>
      <div>=C2=A0</div>
      <div>Currently in Germany there seem to be no general restrictions
        about flying light helis (less than 2 kg) even over inhabited
        terrain. I am not sure though about legal implications of a
        tethering wire or going to higher altitudes. Basic liability
        insurance seems definitely recommended and can be obtained eg by
        joining a model flight club. While hovering over houses after
        sunset with bright green and LED bars on, we were confronted by
        one neighbour who strongly expressed her dislike of the
        activity. People mostly seem to be concerned of "Papparazzi
        drones" invading their precious privacy, the acoustic noise when
        flying low, and surely the fear that these things might end up
        falling onto their heads.</div>
      <div>=C2=A0</div>
      <div>Best 73,<br>
        Markus (DF6NM)<br>
        <br>
      </div>
      -----Urspr=C3=BCngliche Mitteilung----- <br>
      Von: Stefan Sch=C3=A4fer <a class=3D"moz-txt-link-rfc2396E" href=3D=
"mailto:Stefan.Schaefer@iup.uni-heidelberg.de">&lt;Stefan.Schaefer@iup.un=
i-heidelberg.de&gt;</a><br>
      An: rsgb_lf_group <a class=3D"moz-txt-link-rfc2396E" href=3D"mailto=
:rsgb_lf_group@blacksheep.org">&lt;rsgb_lf_group@blacksheep.org&gt;</a><b=
r>
      Verschickt: Di, 6 Aug 2013 1:43 am<br>
      Betreff: Re: LF: Quadrocopter antenna, sri, a bit OT<br>
      <br>
      <div id=3D"AOLMsgPart_1_a4a87010-3a38-4d18-83da-34839e3bbad1">
        <div class=3D"aolReplacedBody" text=3D"#000000" bgcolor=3D"#fffff=
f">Hi
          Warren, LF/VLF,<br>
          <br>
          I just found this: <a moz-do-not-send=3D"true"
            class=3D"aolmail_moz-txt-link-freetext"
            href=3D"http://www.youtube.com/watch?v=3DG3yR-GxD1is"
            target=3D"_blank">http://www.youtube.com/watch?v=3DG3yR-GxD1i=
s</a>=C2=A0
          Take a look at it. I can't find the words. I think i must have
          one :-)<br>
          That must be <u>SEVERAL</u> 100m above ground. I think we
          could even do VLF experiments with such a copter. Maybe a 500m
          vertical? I remember the weight of the wire in my 300m kite
          antenna test was about 1.5 kg, not more. So with 500m we could
          come lower than 5.17 kHz, like i did in 2010/2011.<br>
          <br>
          73, Stefan/DK7FC<br>
          <br>
          <br>
          Am 06.08.2013 01:02, schrieb Warren Ziegler:
          <blockquote type=3D"cite">
            <div dir=3D"ltr">Stefan,
              <div>=C2=A0 =C2=A0 But 100m is not better than your kite
                experiments!</div>
              <div>Yes you gain control but not height.=C2=A0</div>
              <div>You will still need a battery to land the quadcopter
                in the event of a failure of the power carrying wire.</di=
v>
              <div><br>
              </div>
              <div><br>
              </div>
              <div>73 W</div>
            </div>
            <div class=3D"aolmail_gmail_extra"><br>
              <br>
            </div>
            <div class=3D"aolmail_gmail_quote">On Mon, Aug 5, 2013 at 6:5=
3
              PM, Stefan Sch=C3=A4fer <span dir=3D"ltr">&lt;<a
                  moz-do-not-send=3D"true"
                  href=3D"mailto:Stefan.Schaefer@iup.uni-heidelberg.de">S=
tefan.Schaefer@iup.uni-heidelberg.de</a>&gt;</span>
              wrote:<br>
              <blockquote style=3D"BORDER-LEFT: rgb(204,204,204) 1px
                solid; MARGIN: 0pt 0pt 0pt 0.8ex; PADDING-LEFT: 1ex"
                class=3D"aolmail_gmail_quote">
                <div text=3D"#000000" bgcolor=3D"#ffffff">Hi all, <br>
                  <br>
                  I just gathered some informations from the web. Just
                  one example for a, probably, suitable hexacopter to
                  carry a LF transmit antenna. <br>
                  <br>
                  For example a DJI F550, see a video at <a
                    moz-do-not-send=3D"true"
                    href=3D"http://www.youtube.com/watch?v=3DveDrtdE6njo"
                    target=3D"_blank">http://www.youtube.com/watch?v=3Dve=
DrtdE6njo</a>
                  or <a moz-do-not-send=3D"true"
                    href=3D"http://www.youtube.com/watch?v=3D2QC9so2so3Y"
                    target=3D"_blank">http://www.youtube.com/watch?v=3D2Q=
C9so2so3Y</a>).
                  Looks like they can easily lift 1 kg! You can fly
                  about 10 minutes with a 5.3 Ah battery. The battery
                  voltage is to 11.1V...14.8V. So the power consumption
                  may be 200...300 W ! With a compact SMPS on the copter
                  and a 2 wire line it could be possible to carry the
                  antenna. And 100m is no problem too!!<br>
                  I consider to buy one! And look this, most
                  fascinating. <a moz-do-not-send=3D"true"
                    href=3D"http://www.youtube.com/watch?v=3DJecyY79K7kY"
                    target=3D"_blank">http://www.youtube.com/watch?v=3DJe=
cyY79K7kY</a><br>
                  <br>
                  73, Stefan/DK7FC<br>
                  <br>
                  <br>
                  Am 05.08.2013 15:25, schrieb Stefan Sch=C3=A4fer:
                  <blockquote type=3D"cite"><br>
                    Am 04.08.2013 17:52, schrieb DK1IS:
                    <blockquote type=3D"cite">
                      <div>[...]But with nowadays quadrocopters and a
                        "little" reduction of the demands it should be
                        possible to feed them from the ground with DC
                        (or AC plus converters for reduction of current)
                        via 2 wire line and having a good antenna too.<br=
>
                        <br>
                        73,<br>
                        Tom, DK1IS<br>
                      </div>
                    </blockquote>
                    <br>
                    That's it! So, Markus, could you ask your friend
                    abot some technical details? What is the supply
                    voltage of the system and power consumption (or
                    lifetime at a certain battery charge)? Is it
                    possible to lift 1 kg and how does it change the
                    power consumption? It should be no problem to feed
                    DC to the system or a compact power supply in the
                    sky and normal 230V mains at ground (todays PSUs
                    have an input voltage range of 85...240V AC, so a
                    certain voltage drop on the thin wire should be no
                    problem.<br>
                    Maybe you can do some tests?<br>
                    <br>
                    The advatages are clear. A quadrocopter keeps the
                    position and height, even in smaller wind blasts
                    while a balloon bounces left and right. The costs of
                    Helium will quickly overcome the costs for a
                    quadrocopter. Ah and such a project is simply more
                    interesting i guess :-)<br>
                    <br>
                    73, Stefan/DK7FC<br>
                  </blockquote>
                </div>
              </blockquote>
            </div>
            <div class=3D"aolmail_gmail_extra"><br>
              <br clear=3D"all">
            </div>
            <div class=3D"aolmail_gmail_extra"><br>
            </div>
            <div class=3D"aolmail_gmail_extra">-- <br>
              73 Warren K2ORS<br>
              =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 WD2=
XGJ <br>
              =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 WD2=
XSH/23<br>
              =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 WE2=
XEB/2<br>
              =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 WE2=
XGR/1<br>
              <br>
              Re: LF: USA issued 68 to 76 kHz band with 10 W ERP <br>
              Von: Markus Vester &lt;<a moz-do-not-send=3D"true"
                href=3D"mailto:markusvester@aol.com">markusvester@aol.com=
</a>&gt;
            </div>
            <div class=3D"aolmail_gmail_extra">An: rsgb_lf_group &lt;<a
                moz-do-not-send=3D"true"
                href=3D"mailto:rsgb_lf_group@blacksheep.org">rsgb_lf_grou=
p@blacksheep.org</a>&gt;
            </div>
            <div class=3D"aolmail_gmail_extra">Datum: So, 4 Aug 2013 9:47
              am </div>
            <div class=3D"aolmail_gmail_extra">=C2=A0</div>
            <div class=3D"aolmail_gmail_extra">...Yesterday night a frien=
d
              showed me his new GPS-stabilized quadrocopter. It's
              stunning how it could just about be parked in midair,
              despite some lateral winds. Seems that would make a great
              antenna carrier! Not all of the neighbour's seemed to
              enjoy it as much as we did... <br>
              =C2=A0<br>
              Best 73,<br>
              Markus (DF6NM)<br>
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