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Message-ID: <1314792100.61830.YahooMailNeo@web111911.mail.gq1.yahoo.com>
Date: Wed, 31 Aug 2011 05:01:40 -0700 (PDT)
From: Daniele Tincani <danieletincani@yahoo.com>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
In-Reply-To: <4E5CFEEF.6050803@legal-medicine.de>
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Subject: Re: LF: Re: Ferrite wideband antennas?
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=A0=0AHi Peter, LF,=0A=A0=0Ais a specific type of wire recommended (or not =
recommended) for the coil?=0A=A0=0ABest regards=0ADaniele=0A=A0=0A=0AFrom: =
pws <pws@legal-medicine.de>=0ATo: rsgb_lf_group@blacksheep.org=0ASent: Tues=
day, August 30, 2011 5:17 PM=0ASubject: LF: Re: Ferrite wideband antennas?=
=0A=0AHi again Daniele,=0A=0AI forgot some words about shielding.=0A=0ADo n=
ot use solid sheet. I just built a small receiver for rtty at 147 kHz for w=
eather report reception when sailing. Using a fine looking u-shaped copper =
shield the signal went down of some 10 dB even if spaced 4 cm apart from th=
e rod. And it did not improve the SNR considerably.=0A=0AUsing an envelope =
from old SCSI flatline soldered together only at one side the SNR went up o=
f >10 dB inside the house. The effect is incredible. My guess is that Eddy =
currents are responsible for this. So if possible shield your ferrite anten=
na coil by a "feathered", comb-like structure with multiple conductors runn=
ing in parallel around the rod. They may overlap some cm if isolated. And i=
n contrast to solid shielding distance doesn't matter.=0A=0APeter, df3lp
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<html><body><div style=3D"color:#000; background-color:#fff; font-family:ar=
ial, helvetica, sans-serif;font-size:10pt"><div style=3D"RIGHT: auto"><SPAN=
 style=3D"RIGHT: auto"></SPAN>&nbsp;</div>
<div style=3D"RIGHT: auto"><SPAN style=3D"RIGHT: auto">Hi Peter, LF,</SPAN>=
</div>
<div style=3D"RIGHT: auto"><SPAN style=3D"RIGHT: auto"></SPAN>&nbsp;</div>
<div style=3D"RIGHT: auto"><SPAN style=3D"RIGHT: auto">is a specific type<V=
AR id=3Dyui-ie-cursor></VAR> of wire recommended (or not recommended) for t=
he coil?</SPAN></div>
<div style=3D"RIGHT: auto"><SPAN style=3D"RIGHT: auto"></SPAN>&nbsp;</div>
<div style=3D"RIGHT: auto"><SPAN style=3D"RIGHT: auto">Best regards</SPAN><=
/div>
<div style=3D"RIGHT: auto"><SPAN style=3D"RIGHT: auto">Daniele</SPAN></div>
<div style=3D"RIGHT: auto"><SPAN style=3D"RIGHT: auto"></SPAN>&nbsp;</div>
<div style=3D"RIGHT: auto"><BR style=3D"RIGHT: auto"></div>
<DIV style=3D"FONT-SIZE: 10pt; FONT-FAMILY: arial, helvetica, sans-serif">
<DIV style=3D"FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, time=
s, serif"><FONT face=3DArial size=3D2>
<DIV class=3Dhr style=3D"BORDER-RIGHT: #ccc 1px solid; PADDING-RIGHT: 0px; =
BORDER-TOP: #ccc 1px solid; PADDING-LEFT: 0px; FONT-SIZE: 0px; PADDING-BOTT=
OM: 0px; MARGIN: 5px 0px; BORDER-LEFT: #ccc 1px solid; LINE-HEIGHT: 0; PADD=
ING-TOP: 0px; BORDER-BOTTOM: #ccc 1px solid; HEIGHT: 0px" readonly=3D"true"=
 contenteditable=3D"false"></DIV><B><SPAN style=3D"FONT-WEIGHT: bold">From:=
</SPAN></B> pws &lt;pws@legal-medicine.de&gt;<BR><B><SPAN style=3D"FONT-WEI=
GHT: bold">To:</SPAN></B> rsgb_lf_group@blacksheep.org<BR><B><SPAN style=3D=
"FONT-WEIGHT: bold">Sent:</SPAN></B> Tuesday, August 30, 2011 5:17 PM<BR><B=
><SPAN style=3D"FONT-WEIGHT: bold">Subject:</SPAN></B> LF: Re: Ferrite wide=
band antennas?<BR></FONT><BR>Hi again Daniele,<BR><BR>I forgot some words a=
bout shielding.<BR><BR>Do not use solid sheet. I just built a small receive=
r for rtty at 147 kHz for weather report reception when sailing. Using a fi=
ne looking u-shaped copper shield the signal went down of some 10 dB even i=
f spaced
 4 cm apart from the rod. And it did not improve the SNR considerably.<BR><=
BR>Using an envelope from old SCSI flatline soldered together only at one s=
ide the SNR went up of &gt;10 dB inside the house. The effect is incredible=
. My guess is that Eddy currents are responsible for this. So if possible s=
hield your ferrite antenna coil by a "feathered", comb-like structure with =
multiple conductors running in parallel around the rod. They may overlap so=
me cm if isolated. And in contrast to solid shielding distance doesn't matt=
er.<BR><BR>Peter, df3lp<BR><BR><BR><BR></DIV></DIV></div></body></html>
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