Hi again Fabio and Guy,
Oh, I didn?t know you were surrounded by so many buildings close to your QTH,
Fabio. It will therefore give you a very complex take-off picture. If you have
a 3-4 el beam on 20m it will give you the maximum signal in approx 12 degrees
anyhow , but you will have a bit worse front to back and a bit worse gain than
you will have if you put up an antenna with "nothing" surrounding your QTH.
But you have to deal with the situation and you will have many good QSO:s in
the future.
I can tell you, I have two QTH:s, one close to the town with many houses around
my QTH, and one at my summer-QTH 100m away from the Baltic sea. And
what a difference. With the same type of antenna at equal higth I have to use
the PA (+15 dB) at my ordinary QTH and doesn?t come up to the same signal as I
get from my summer-QTH without the PA.
73 de Owe /SM3CWE
----- Original Message -----
From: "Guy Olinger, K2AV" <olinger@bellsouth.net>
> 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>
> > 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
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