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Date: Sun, 04 Aug 2013 17:52:26 +0200
From: DK1IS <DK1IS@kabelmail.de>
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Subject: Re: LF: USA issued 68 to 76 kHz band with 10 W ERP
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To all quadrocopter pilots:

Why not to carry the flight energy from ground to the helicopter via the=20
antenna wire(s)? At the end of WW2 the German navy developed a=20
helicopter antenna for portable use on VLF consisting of a bulky 3 phase=20
AC motor with two counter rotating rotors and some stabilizers being fed=20
by three antenna wires from three isolated hoist gears in a triangle=20
array at ground. Separation between AC power and VLF by high pass=20
filters, maximum flight height about 1200 m! (*) Fortunately this=20
arrangement didn=B4t come into use anymore - probably it was a last act o=
f=20
desperation. Furthermore the antenna shape was not optimum due to=20
unfavourable distribution of capacity. But with nowadays quadrocopters=20
and a "little" reduction of the demands it should be possible to feed=20
them from the ground with DC (or AC plus converters for reduction of=20
current) via 2 wire line and having a good antenna too.

73,
Tom, DK1IS
www.qrz.com/db/dk1is

(*) see "Hubschrauberantenne" in Hille, Karl H.; Krischke, A.: Das=20
Antennen-Lexikon; Baden-Baden 1988, ISBN 3-88180-304-1


Am 04.08.2013 16:02, schrieb Warren Ziegler:
> Markus, Stefan, LF,
>
>       Please keep in mind that 10W represents an upper limit, we are=20
> free to run anything below that!
>
>      About Quadcopters - the limitation is the life of the battery -=20
> which is on the order of 15 minutes, even if it could lift enough=20
> weight, it wouldn't last long! (The more weight it must lift the=20
> higher the battery drain!)
>
>      A better solution might be a remote controlled airship (zeppelin)=20
> where the helium supplies the lift and motors provide steering only.
>
>
> 73 Warren K2ORS
>
>
>
> On Sun, Aug 4, 2013 at 7:39 AM, Stefan Sch=E4fer=20
> <Stefan.Schaefer@iup.uni-heidelberg.de=20
> <mailto:Stefan.Schaefer@iup.uni-heidelberg.de>> wrote:
>
>     Hi Markus,
>
>     Am 04.08.2013 09:46, schrieb Markus Vester:
>>     Stefan, 10 W ERP is not that hard - anyone who can radiate 80 W
>>     ERP on 136 will be able to do 10 W on half the frequency ;-))
>     Oh yes indeed. The radiation resistance of the wire is about 1/4
>     and the needed L is about 4x, so the coil losses will be 4x higher
>     too. The ground losses may drop a bit. Then it depends on the
>     ratio of coil losses to ground losses. So 80W is realistic :-)
>
>     I don't know anything about LF propagation on that band. Is it
>     much different to 2200m? And what are the distance records?
>
>>     Yesterday night a friend 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...
>     MOST interesting! Did you ask him what the weight can be lifted?
>     And will it still be stable then? Is it expensive? Do you fear
>     some EMC problems? (The topic should be discussed in a new subject
>     then)
>
>     73, Stefan/DK7FC
>
>>     Best 73,
>>     Markus (DF6NM)
>
>
>
>
> --=20
> 73 Warren K2ORS
>                 WD2XGJ
>                 WD2XSH/23
>                 WE2XEB/2
>                 WE2XGR/1
>


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    <div class="moz-cite-prefix">To all quadrocopter pilots:<br>
      <br>
      Why not to carry the flight energy from ground to the helicopter
      via the antenna wire(s)? At the end of WW2 the German navy
      developed a helicopter antenna for portable use on VLF consisting
      of a bulky 3 phase AC motor with two counter rotating rotors and
      some stabilizers being fed by three antenna wires from three
      isolated hoist gears in a triangle array at ground. Separation
      between AC power and VLF by high pass filters, maximum flight
      height about 1200 m! (*) Fortunately this arrangement didn&acute;t come
      into use anymore - probably it was a last act of desperation.
      Furthermore the antenna shape was not optimum due to unfavourable
      distribution of capacity. 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>
      <a class="moz-txt-link-abbreviated" href="http://www.qrz.com/db/dk1is">www.qrz.com/db/dk1is</a><br>
      <br>
      (*) see "Hubschrauberantenne" in Hille, Karl H.; Krischke, A.: Das
      Antennen-Lexikon; Baden-Baden 1988, ISBN 3-88180-304-1<br>
      <br>
      <br>
      Am 04.08.2013 16:02, schrieb Warren Ziegler:<br>
    </div>
    <blockquote
cite="mid:CAMFjj72u6XmM=tW1moV87vwYGDvQv0jpbAtKm1pHimx1FZxbFg@mail.gmail.com"
      type="cite">
      <div dir="ltr">Markus, Stefan, LF,
        <div><br>
        </div>
        <div>&nbsp; &nbsp; &nbsp; Please keep in mind that 10W represents an upper
          limit, we are free to run anything below that!</div>
        <div><br>
        </div>
        <div>&nbsp; &nbsp; &nbsp;About Quadcopters - the limitation is the life of the
          battery - which is on the order of 15 minutes, even if it
          could lift enough weight, it wouldn't last long! (The more
          weight it must lift the higher the battery drain!)</div>
        <div><br>
        </div>
        <div>&nbsp; &nbsp; &nbsp;A better solution might be a remote controlled airship
          (zeppelin) where the helium supplies the lift and motors
          provide steering only.</div>
        <div><br>
        </div>
        <div><br>
        </div>
        <div>73 Warren K2ORS</div>
        <div><br>
        </div>
        <div>&nbsp;&nbsp;</div>
      </div>
      <div class="gmail_extra"><br>
        <br>
        <div class="gmail_quote">On Sun, Aug 4, 2013 at 7:39 AM, Stefan
          Sch&auml;fer <span dir="ltr">&lt;<a moz-do-not-send="true"
              href="mailto:Stefan.Schaefer@iup.uni-heidelberg.de"
              target="_blank">Stefan.Schaefer@iup.uni-heidelberg.de</a>&gt;</span>
          wrote:<br>
          <blockquote class="gmail_quote" style="margin:0 0 0
            .8ex;border-left:1px #ccc solid;padding-left:1ex">
            <div bgcolor="#ffffff" text="#000000">
              Hi Markus, <br>
              <br>
              Am 04.08.2013 09:46, schrieb Markus Vester:
              <div class="im">
                <blockquote type="cite">
                  <div>&nbsp;</div>
                  <div><font face="Arial">Stefan, 10 W ERP is not that
                      hard -
                      anyone who can radiate 80 W ERP on 136 will be
                      able to do 10 W&nbsp;on half
                      the frequency ;-))</font></div>
                </blockquote>
              </div>
              Oh yes indeed. The radiation resistance of the wire is
              about 1/4 and
              the needed L is about 4x, so the coil losses will be 4x
              higher too. The
              ground losses may drop a bit. Then it depends on the ratio
              of coil
              losses to ground losses. So 80W is realistic :-)<br>
              <br>
              I don't know anything about LF propagation on that band.
              Is it much
              different to 2200m? And what are the distance records? <br>
              <div class="im">
                <br>
                <blockquote type="cite">
                  <div><font face="Arial"> Yesterday night a
                      friend&nbsp;showed
                      me&nbsp;his new GPS-stabilized quadrocopter. It's
                      stunning how it&nbsp;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&nbsp;seemed
                      to&nbsp;enjoy it&nbsp;as much as we did... </font></div>
                </blockquote>
              </div>
              MOST interesting! Did you ask him what the weight can be
              lifted? And
              will it still be stable then? Is it expensive? Do you fear
              some EMC
              problems? (The topic should be discussed in a new subject
              then)<br>
              <br>
              73, Stefan/DK7FC<br>
              <br>
              <blockquote type="cite">
                <div>&nbsp;</div>
                <div><font face="Arial">Best 73,</font></div>
                <div><font face="Arial">Markus (DF6NM)</font></div>
              </blockquote>
            </div>
          </blockquote>
        </div>
        <br>
        <br clear="all">
        <div><br>
        </div>
        -- <br>
        73 Warren K2ORS<br>
        &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; WD2XGJ <br>
        &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; WD2XSH/23<br>
        &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; WE2XEB/2<br>
        &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; WE2XGR/1<br>
        <br>
        &nbsp;
      </div>
    </blockquote>
    <br>
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