In an urban setting, with so much clutter on the ground, a useful assumption
for conservative estimating is that the energy radiating from the antenna at an
angle below the horizon will be mostly lost.
Further, since there are many ways to reradiate energy from the clutter, the
energy lost from what would have been the main pattern will fill in expected
deep nulls to very odd directions, giving the appearance that the antenna is
missing some degree of front-to-back or front-to-side, in a rather random
fashion.
Separating this from the antenna's actual performance would be close to
impossible.
As previously posted, the main lobe above the horizon would be OK using the 25m
elevation, and defining your ground as "very, very poor".
73, Guy.
>
> From: Fabio <fabio.mantovani@inwind.it>
To: <antennaware@contesting.com>
> Date: 2003/04/17 Thu PM 12:45:28 EDT
> To: "owe persson" <sm3cwe.owe@telia.com>, antennaware@contesting.com
> Subject: Re: [Antennaware] Height
>
> At 16.16 17.04.2003 +0200, you wrote:
> >Hi,
> >It depends on how much of steel and things you have in the house,
> >but I should think that you can count on 25 mtrs when you are doing
> >your calculations, e g your antenna will be on >1 lambda on 14 MHz
> >and you will have a main-takeoff of approx 12 degrees and one takeoff
> >at 38 degrees approx about 4 dB down from mainloob.
> >Good luck with the construction!
> >73 de Owe /SM3CWE
>
> Thanks Owe!
> Moreover, I am in a city, so I think that modeling urban conditions becomes
> too complex, for me and for NEC probably
> I will model @25m and I'll take the conclusions with a little of
> pessimism... that could be a good compromise HI
> Thanks again,
> Ciao
> Fabio IZ4AFW
>
>
> --
> EMail fabio.mantovani@inwind.it
> iz4afw@amsat.org
> Home Page http://www.qsl.net/iz4afw
>
>
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>
73, Guy
K2AV
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