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Date: Sun, 1 May 2011 13:53:13 +0100 (BST)
From: M0FMT <m0fmt@yahoo.co.uk>
To: rsgb_lf_group@blacksheep.org
In-Reply-To: <E853CBB550F8486C860CC25E3BBC0144@JimPC>
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Subject: Re: LF: ERP estimation
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Thank you both for the information I think I understand it to a level that=
 I can=20
calculate an ERP value for my antenna.
=A073 es GL Pete M0FMT IO91UX=20




________________________________
From: James Moritz <james.moritz@btopenworld.com>
To: rsgb_lf_group@blacksheep.org
Sent: Sun, 1 May, 2011 12:53:38
Subject: Re: LF: ERP estimation

Dear Pete, LF Group,

> There must be some software written that does this?

You can use NEC-based antenna simulation software (EZNEC, etc.) to obtain=
 Rrad=20
for your antenna, by running an "SWR plot" using perfect conductors and pe=
rfect=20
ground. The resistive component of the antenna impedance given by the simu=
lator=20
is then equal to the radiation resistance, since there are no other source=
s of=20
loss. This is quite useful for more complicated antenna configurations wit=
h=20
multiple wires, elevated feeds, etc., but for most simple wire antennas,=
 just=20
calculating Heff as the average height of the wires gives nearly the same=
=20
result, and like Andy says, it is easier and quicker just to use a calcula=
tor.

Cheers, Jim Moritz
73 de M0BMU

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<html><head><style type=3D"text/css"><!-- DIV {margin:0px;} --></style></h=
ead><body><div style=3D"font-family:arial, helvetica, sans-serif;font-size=
:10pt"><DIV></DIV>
<DIV>Thank you both for the information I think I understand it to a level=
 that I can calculate an ERP value for my antenna.<BR>&nbsp;</DIV>73 es GL=
 Pete M0FMT IO91UX=20
<DIV><BR></DIV>
<DIV style=3D"FONT-FAMILY: arial, helvetica, sans-serif; FONT-SIZE: 10pt">=
<BR>
<DIV style=3D"FONT-FAMILY: arial, helvetica, sans-serif; FONT-SIZE: 13px">=
<FONT size=3D2 face=3DTahoma>
<HR SIZE=3D1>
<B><SPAN style=3D"FONT-WEIGHT: bold">From:</SPAN></B> James Moritz &lt;jam=
es.moritz@btopenworld.com&gt;<BR><B><SPAN style=3D"FONT-WEIGHT: bold">To:<=
/SPAN></B> rsgb_lf_group@blacksheep.org<BR><B><SPAN style=3D"FONT-WEIGHT:=
 bold">Sent:</SPAN></B> Sun, 1 May, 2011 12:53:38<BR><B><SPAN style=3D"FON=
T-WEIGHT: bold">Subject:</SPAN></B> Re: LF: ERP estimation<BR></FONT><BR>D=
ear Pete, LF Group,<BR><BR>&gt; There must be some software written that=
 does this?<BR><BR>You can use NEC-based antenna simulation software (EZNE=
C, etc.) to obtain Rrad for your antenna, by running an "SWR plot" using=
 perfect conductors and perfect ground. The resistive component of the ant=
enna impedance given by the simulator is then equal to the radiation resis=
tance, since there are no other sources of loss. This is quite useful for=
 more complicated antenna configurations with multiple wires, elevated fee=
ds, etc., but for most simple wire antennas, just calculating Heff as the=
 average height of
 the wires gives nearly the same result, and like Andy says, it is easier=
 and quicker just to use a calculator.<BR><BR>Cheers, Jim Moritz<BR>73 de=
 M0BMU<BR><BR><BR><BR></DIV></DIV></div></body></html>

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