From: Rik Strobbe <Rik.Strobbe@fys.kuleuven.be>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
Thread-Topic: LF: Antennas on low bands : the Siegel and Labus books.
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Date: Sat, 30 May 2015 16:58:05 +0000
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Subject: RE: LF: Antennas on low bands : the Siegel and Labus books.
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Hi Tom, Bob,


I had a look in my Rothammel Antennenbuch (geniune "Milit=E4rverlag der Deu=
tschen Demokratischen Republik" version, 1974) and indeed it states 0.007 l=
ambda height.

But what about ground losses if the DDRR antenna uses the ground as counter=
poise?

There is also a version with a second ring as counterpoise, but I'm afraid =
that this even this version needs to be at sufficient height (in wavelength=
s) to avoid ground losses.

Apart from that: the only way to find out if it works is trying (probieren =
geht =FCber studieren). If anyone has experience with a DDRR antenna on 137=
kHz or 475kHz I will be happy to add a chapter to my antenna webpages.

0.007 lambda is barely 4.4m height at 475kHz ... should be easy. For the 0.=
25 lambda perimeter a 50 x 50 m open area is needed, only for the larger ba=
ckyards.


73, Rik  ON7YD - OR7T

________________________________
Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org=
] namens DK1IS [DK1IS@kabelmail.de]
Verzonden: vrijdag 29 mei 2015 23:45
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: Antennas on low bands : the Siegel and Labus books.

Am 29.05.2015 um 21:59 schrieb Rik Strobbe:

Hi Bob,


small is a relative thing on LF.

A DDRR with a perimeter of 0.25 lambda and a height of 0.025 lamdba is inde=
ed small on 144MHz, but on 137kHz the perimeter becomes 550m and the height=
 a respectable 55m.

Not a backyard antenna ...


73, Rik  ON7YD - OR7T

Hi Rik and Bob,

acoording to Rothammel et alt. in my former 10 meter version I used a heigh=
t of 0,007 lambda, so you should need rods of only 15,4 meters - but anyway=
 ...  ;-)

73,
Tom, DK1IS

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1">
</head>
<body bgcolor=3D"#ffffff" fPStyle=3D"1" ocsi=3D"0">
<div style=3D"direction: ltr;font-family: Tahoma;color: #000000;font-size: =
10pt;">
<p>Hi Tom, Bob,</p>
<p>&nbsp;</p>
<p>I had a look in my Rothammel Antennenbuch (geniune &quot;Milit=E4rverlag=
 der Deutschen Demokratischen Republik&quot; version, 1974) and indeed it s=
tates 0.007 lambda height.</p>
<p>But what about ground losses if the DDRR antenna uses the ground as coun=
terpoise?</p>
<p>There is also a version with a second ring as counterpoise, but I'm afra=
id that this even this version needs to be at sufficient height (in wavelen=
gths) to avoid ground losses.</p>
<p>Apart from that: the only way to find out if it works is trying (probier=
en geht =FCber studieren). If anyone has experience with a DDRR antenna on =
137kHz or 475kHz I will be happy to add a chapter to my antenna webpages.</=
p>
<p>0.007 lambda is barely 4.4m height at 475kHz ... should be easy. For the=
 0.25 lambda perimeter a 50 x 50 m open area is needed,&nbsp;only for the l=
arger backyards.</p>
<p>&nbsp;</p>
<p>73, Rik&nbsp; ON7YD - OR7T</p>
<div style=3D"FONT-SIZE: 16px; FONT-FAMILY: Times New Roman; COLOR: #000000=
">
<hr tabindex=3D"-1">
<div id=3D"divRpF909434" style=3D"DIRECTION: ltr"><font color=3D"#000000" s=
ize=3D"2" face=3D"Tahoma"><b>Van:</b> owner-rsgb_lf_group@blacksheep.org [o=
wner-rsgb_lf_group@blacksheep.org] namens DK1IS [DK1IS@kabelmail.de]<br>
<b>Verzonden:</b> vrijdag 29 mei 2015 23:45<br>
<b>Aan:</b> rsgb_lf_group@blacksheep.org<br>
<b>Onderwerp:</b> Re: LF: Antennas on low bands : the Siegel and Labus book=
s.<br>
</font><br>
</div>
<div></div>
<div>
<div class=3D"moz-cite-prefix">Am 29.05.2015 um 21:59 schrieb Rik Strobbe:<=
br>
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<p>Hi Bob,</p>
<p>&nbsp;</p>
<p>small is a relative thing on LF.</p>
<p>A DDRR with a perimeter of 0.25 lambda and a height of 0.025 lamdba is i=
ndeed small on 144MHz, but on 137kHz the perimeter becomes 550m and the hei=
ght a respectable 55m.</p>
<p>Not a backyard antenna ...</p>
<p>&nbsp;</p>
<p>73, Rik&nbsp; ON7YD - OR7T</p>
<br>
</div>
</blockquote>
Hi Rik and Bob,<br>
<br>
acoording to Rothammel et alt. in my former 10 meter version I used a heigh=
t of 0,007 lambda, so you should need rods of only 15,4 meters - but anyway=
 ...&nbsp; ;-)<br>
<br>
73,<br>
Tom, DK1IS<br>
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</body>
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