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Date: Fri, 22 Jan 2010 08:32:13 +0000
Message-ID: <fc7eccec1001220032n479948e0r952ce47d5420acbd@mail.gmail.com>
From: Andy Talbot <andy.g4jnt@googlemail.com>
To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: ERP<>EMRP
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Well, yes it is I suppose if you lump antenna directivity into the
equation.
I^2.R is the actual power radiated.
Which direction it then goes is a different issue.

Anyway, what is the true directivity figure to use for a monopole ?
A very short dipole has 1.5 times directivity.  Therefore a short monopole
over perfect ground ought to have 3 times.  Neither of which is 1.83

Andy
www.g4jnt.com

This email has been scanned for damaging side-effects by the health and
safety police, is guaranteed to contain no substances hazardous to health,
but may contribute to dissolving the nether and polar regions


2010/1/21 Stefan Sch=E4fer <schaefer@hst.tu-darmstadt.de>

> Hi Andy,
>
> Isn't it, the ERP is I^2*Rrad*1,83, if we assume a vertical antenna?
>
> 73, Stefan
>
> ________________________________
>
> Von: owner-rsgb_lf_group@blacksheep.org im Auftrag von Andy Talbot
> Gesendet: Do 21.01.2010 20:27
> An: rsgb_lf_group@blacksheep.org
> Betreff: Re: LF: Re: M0BMU - any chance of some new ERP estimates please=
?
>
>
> So go on:  argue against the Rrad (an exact figure derived from basic
> electromag theory) and Rloss (easily measurable, called Ohms law) way of
> getting antenna efficiency.
>
> Or  ERP =3D   I^2 . Rrad   where I is measurable.
>
> Only uncertainty in any of these techniques is the effective height of=
 the
> antenna used to get Rrad, but absolute worst case, can only ever lead to=
 6dB
> error.  The difference between no top hat and an infinite top hat
>
> Andy
> www.g4jnt.com <http://www.g4jnt.com/>
>
>
>

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<div>Well, yes it is I suppose if you lump antenna directivity into the eq=
uation.=A0 </div>
<div>I^2.R is the actual power radiated. </div>
<div>Which direction=A0it then goes is a different issue.</div>
<div>=A0</div>
<div>Anyway, what is the true directivity figure to use for a monopole ?</=
div>
<div>A very short dipole has 1.5 times directivity.=A0 Therefore a short=
 monopole over perfect ground ought to have 3 times.=A0 Neither of which=
 is 1.83</div>
<div><br clear=3D"all">Andy<br><a href=3D"http://www.g4jnt.com">www.g4jnt.=
com</a><br><br>This email has been scanned for damaging side-effects by th=
e health and safety police, is guaranteed to contain no substances hazardo=
us to health, but may contribute to dissolving the nether and polar region=
s<br>
<br><br></div>
<div class=3D"gmail_quote">2010/1/21 Stefan Sch=E4fer <span dir=3D"ltr">&l=
t;<a href=3D"mailto:schaefer@hst.tu-darmstadt.de">schaefer@hst.tu-darmstad=
t.de</a>&gt;</span><br>
<blockquote style=3D"BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8e=
x; PADDING-LEFT: 1ex" class=3D"gmail_quote">Hi Andy,<br><br>Isn&#39;t it,=
 the ERP is I^2*Rrad*1,83, if we assume a vertical antenna?<br><br>73, Ste=
fan<br>
<br>________________________________<br><br>Von: <a href=3D"mailto:owner-r=
sgb_lf_group@blacksheep.org">owner-rsgb_lf_group@blacksheep.org</a> im Auf=
trag von Andy Talbot<br>Gesendet: Do 21.01.2010 20:27<br>An: <a href=3D"ma=
ilto:rsgb_lf_group@blacksheep.org">rsgb_lf_group@blacksheep.org</a><br>
Betreff: Re: LF: Re: M0BMU - any chance of some new ERP estimates please?<=
br><br><br>So go on: =A0argue against the Rrad (an exact figure derived fr=
om basic electromag theory) and Rloss (easily measurable, called Ohms law)=
 way of getting antenna efficiency.<br>
<br>Or =A0ERP =3D =A0 I^2 . Rrad =A0 where I is measurable.<br><br>Only un=
certainty in any of these techniques is the effective height of the antenn=
a used to get Rrad, but absolute worst case, can only ever lead to 6dB err=
or. =A0The difference between no top hat and an infinite top hat<br>
<br>Andy<br><a href=3D"http://www.g4jnt.com/" target=3D"_blank">www.g4jnt.=
com</a> &lt;<a href=3D"http://www.g4jnt.com/" target=3D"_blank">http://www=
.g4jnt.com/</a>&gt;<br><br><br></blockquote></div><br>

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