To: rsgb_lf_group@yahoogroups.co.uk, rsgb_lf_group@blacksheep.org
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 <671a3724-1b74-e3e3-e08e-5d0c8fab73f9@kabelmail.de>
 <4AB40CA9-ECCF-4A39-B02F-7CE43CD545C8@gmail.com>
From: DK1IS <DK1IS@kabelmail.de>
Message-ID: <c0f51508-2717-d902-d93b-3393c35c4540@kabelmail.de>
Date: Sun, 28 Aug 2016 15:13:20 +0200
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Subject: LF: Re: LA1BCN on 630m, earth dipole
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Hello John,

having installed the latest remote RX system only one week ago I=C2=B4m s=
till=20
in a very early state of a learning process ;-). First of all the=20
configuration used here:

Living in an urban region of Amberg I have to use whatever is possible.=20
Please have a look to the satellite foto on my QRZ.com site with the=20
highest resolution. I own the terrace house with the solar panel array=20
on the roof. Moving the picture to the right you will see a row of 14=20
garages from ferroconcrete (thank Goodness without any utility mains!),=20
the fourth from the top is mine having something on its roof. It=C2=B4s a=
n=20
older picture with ony a small solar panel for the remote controlled=20
door opener - meanwhile the roof is filled pretty good! The earth dipole=20
is laid out on the ground parallel to the garage row at its lower rim,=20
true bearing of the wire being 150=C2=B0<>330=C2=B0 . It=C2=B4s fed in my=
 garage via a=20
ferrite transfomer with 12 turns, the secondary having 4 turns for the=20
Perseus RX which is a compromise for the earth dipole impedances=20
measured on VLF, LF and MF. So the "dipole" looks HF-wise more like a=20
Windom, the upper branch having about 11 m, the lower one about 31 m=20
length. Each end has a grounding post (originally threaded metal hulls=20
for parasols) which is 0.6 m long and screwed into the soil, connected=20
to the dipole via a relay contact so that I can remotely define the=20
grounding condition of each branch. In this way I can change between=20
"earth dipole" (both ends grounded), "Windom on ground" (both ends free)=20
and something like "Mini-Beverage with special feeding" (right side or=20
left side grounded) - and all of them loaded capacitivey and inductively=20
by 14 ferroconcrete garages ...
Each configuration has its own characteristic which in addition depends=20
on frequency - it remains a lot to learn about it! Besides the earth=20
dipole there a two more antennas on the garage roof: an Miniwhip from=20
Bonito and a small fixed passive loop with 2 sqm winding area. Up to now=20
I simply change the antennas via the remote control until the best SNR=20
is achieved.

Concerning the directivity of the "real" earth dipole: it seems=20
significant on VLF, LF and MF where it forms a large lossy loop throgh=20
the ground. For example with the earth dipole I can=C2=B4t see the Russia=
n=20
Alpha stations which are usually strong with the Miniwhip on the garage=20
roof. On the other hand DHO38 is coming stronger with the earth dipole -=20
and the very LA1BCN last night. On HF the directivity seems to be not=20
very significant but up to now I have no general idea about this.

Sorry - it would be fine to have an additional earth dipole at right=20
angles to the existing one but the satellite foto shows why this is=20
nearly impossible! But perhaps there will follow another remote antanna=20
on the garage roof with a ferrite rod turnable in azimuth and elevation=20
- there are two more free channels on my 433 MHz remote control ;-)

73 and hpe to cuagn!

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


Am 28.08.2016 um 11:16 schrieb John Rabson john.rabson07@gmail.com=20
[rsgb_lf_group]:
>
> Tom,
>
> Does your earth dipole antenna show significant directivity? Some=20
> years ago, a group of cave radio enthusiasts conducted measurements on=20
> a 50 m long earth dipole on frequencies from 87 to 648 kHz and with=20
> various orientations, on our local cricket pitch (with permission).=20
> The received field strength exhibited significant minima of as much as=20
> 25 dB.
>
> Would another such dipole at right angles to the existing one show any=20
> difference on Geir=E2=80=99s signal?
>
> 73 John F5VLF/G3PAI
> Cave Radio & Electronics Group and formerly underground communications=20
> specialist for Suffolk Radio Amateurs Emergency Network
>


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    <div class=3D"moz-cite-prefix">Hello John,<br>
      <br>
      having installed the latest remote RX system only one week ago I=C2=
=B4m
      still in a very early state of a learning process ;-). First of
      all the configuration used here:<br>
      <br>
      Living in an urban region of Amberg I have to use whatever is
      possible. Please have a look to the satellite foto on my QRZ.com
      site with the highest resolution. I own the terrace house with the
      solar panel array on the roof. Moving the picture to the right you
      will see a row of 14 garages from ferroconcrete (thank Goodness
      without any utility mains!), the fourth from the top is mine
      having something on its roof. It=C2=B4s an older picture with ony a
      small solar panel for the remote controlled door opener -
      meanwhile the roof is filled pretty good! The earth dipole is laid
      out on the ground parallel to the garage row at its lower rim,
      true bearing of the wire being 150=C2=B0&lt;&gt;330=C2=B0 . It=C2=B4=
s fed in my
      garage via a ferrite transfomer with 12 turns, the secondary
      having 4 turns for the Perseus RX which is a compromise for the
      earth dipole impedances measured on VLF, LF and MF. So the
      "dipole" looks HF-wise more like a Windom, the upper branch having
      about 11 m, the lower one about 31 m length. Each end has a
      grounding post (originally threaded metal hulls for parasols)
      which is 0.6 m long and screwed into the soil, connected to the
      dipole via a relay contact so that I can remotely define the
      grounding condition of each branch. In this way I can change
      between "earth dipole" (both ends grounded), "Windom on ground"
      (both ends free) and something like "Mini-Beverage with special
      feeding" (right side or left side grounded) - and all of them
      loaded capacitivey and inductively by 14 ferroconcrete garages ...
      <br>
      Each configuration has its own characteristic which in addition
      depends on frequency - it remains a lot to learn about it! Besides
      the earth dipole there a two more antennas on the garage roof: an
      Miniwhip from Bonito and a small fixed passive loop with 2 sqm
      winding area. Up to now I simply change the antennas via the
      remote control until the best SNR is achieved.<br>
      <br>
      Concerning the directivity of the "real" earth dipole: it seems
      significant on VLF, LF and MF where it forms a large lossy loop
      throgh the ground. For example with the earth dipole I can=C2=B4t s=
ee
      the Russian Alpha stations which are usually strong with the
      Miniwhip on the garage roof. On the other hand DHO38 is coming
      stronger with the earth dipole - and the very LA1BCN last night.
      On HF the directivity seems to be not very significant but up to
      now I have no general idea about this.<br>
      <br>
      Sorry - it would be fine to have an additional earth dipole at
      right angles to the existing one but the satellite foto shows why
      this is nearly impossible! But perhaps there will follow another
      remote antanna on the garage roof with a ferrite rod turnable in
      azimuth and elevation - there are two more free channels on my 433
      MHz remote control ;-)<br>
      <br>
      73 and hpe to cuagn!<br>
      <br>
      Tom, DK1IS<br>
      <a class=3D"moz-txt-link-abbreviated" href=3D"http://www.qrz.com/db=
/dk1is">www.qrz.com/db/dk1is</a><br>
      <br>
      <br>
      <br>
      <br>
      <br>
      Am 28.08.2016 um 11:16 schrieb John Rabson <a class=3D"moz-txt-link=
-abbreviated" href=3D"mailto:john.rabson07@gmail.com">john.rabson07@gmail=
..com</a>
      [rsgb_lf_group]:<br>
    </div>
    <blockquote
      cite=3D"mid:4AB40CA9-ECCF-4A39-B02F-7CE43CD545C8@gmail.com"
      type=3D"cite"> <span style=3D"display:none">=C2=A0</span>
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          <div id=3D"ygrp-text">
            <p>Tom,<br>
              <br>
              Does your earth dipole antenna show significant
              directivity? Some years ago, a group of cave radio
              enthusiasts conducted measurements on a 50 m long earth
              dipole on frequencies from 87 to 648 kHz and with various
              orientations, on our local cricket pitch (with
              permission). The received field strength exhibited
              significant minima of as much as 25 dB.<br>
              <br>
              Would another such dipole at right angles to the existing
              one show any difference on Geir=E2=80=99s signal?<br>
              <br>
              73 John F5VLF/G3PAI<br>
              Cave Radio &amp; Electronics Group and formerly
              underground communications specialist for Suffolk Radio
              Amateurs Emergency Network<br>
            </p>
          </div>
        </div>
      </div>
    </blockquote>
    <br>
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