Jim,
I'm tilting the entire array in my simulation. I forgot to mention in my
earlier email I'm simulating the array on 20M. At 0 degrees elevation or
tilt (E) the vertical beamwidth (VB) is 5.4 degrees, the horizontal
beamwidth (HB) is 31 degrees and the gain in dbi (G) is 21.5 (according to
EZNEC). At E=16, VB=24, HB=32 and G=17.2.
For comparison, I simulated a single antenna at 65' and stacked antennas at
65 and 110'. For the single antenna, VB=15, HB=57 and G=14.3. For the
stacked antennas, VB=11, HB=56 and G=16.8.
Comparing the stacked antennas against the 6 antenna array tilted at 16
degrees elevation, the array's vertical beamwidth is much wider and
horizontal beamwidth is much narrower for about the same amount of gain.
For my money, I'd probably go with the stacked antennas. But then my money
is limited. If it wasn't, I'd probably have 25 acres on a hilltop and would
build something similar just for fun.
Like others, I've wondered if the 5 degree take-off angle of this array (at
0 degrees tilt) is too low to be practical. Then I remembered the signal
that Lou, EA3JE has with his 6/6/6 stack at 250'. He is always the loudest
European on 20M when he's on the air.
Clay
----- Original Message -----
From: "Jim Lux" <jimlux@earthlink.net>
To: "Clay Curtiss W7CE" <w7ce@curtiss.net>; "'tower'"
<towertalk@contesting.com>
Sent: Wednesday, December 28, 2005 8:57 AM
Subject: Re: [TowerTalk] Holy SteppIR!
> At 06:32 PM 12/27/2005, Clay Curtiss W7CE wrote:
> >My simulations indicate that as you adjust the array elevation
> >above 5 degrees the vertical lobe begins to broaden.
>
> How did you slew the array vertically? By tilting or by phasing the
feeds?
>
>
>
> > At about
> >16 degrees elevation, the vertical 3 db beamwidth is 24
> >degrees (from 3 to 27 degrees). It's not the prettiest pattern one
> >has ever seen, but it should work quite nicely for general purpose
> >dxing and/or contesting.
>
> I assume the horizontal beamwidth is approximately similar? So, to a first
> order, this works out to about 20dBi gain?
>
> Assuming he's running 1500W, that's a fairly impressive 150kW EIRP.
>
>
>
> >Clay
> >
> > >
> > > Yes, that's absolutely right, Jim. I am guilty of thinking "in the
> > > box". If you remove the straight jacket of the conventional Yagi
> > > with fixed tuning/phasing, and exploit the large design space
> > > allowed by the independent element length control, you can
>
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