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[TowerTalk] 3el electrically steerible yagi?

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Subject: [TowerTalk] 3el electrically steerible yagi?
From: (Richard Karlquist)
Date: Tue, 29 Jan 2002 23:15:55 -0800
I have an array like this, except it has 7
elements.  One in the center and 6 in a
circle of 3/4 wl diameter.  However, it 
is an all driven array, not parasitic.
There are 3 phasing networks.  One fires
in the direction of any of the six outer
elements (selectable) with 9 dB gain over
an individual vertical.  The second phasing
network fires in between outer elements with
8 dB gain.  The third phasing network is
omni directional with 2 dB gain.  I have
a 40 meter version of this on the air, 
an 80 meter version is under construction,
and a 160 meter version is being planned.
I also have a contingency plan for 60 meters,
if we get that band.

I fooled around on EZNEC with parasitic
excitation and I was able get within a dB or
two of the driven gain that way, but then I would
have to worry about tuning the elements.  With
a driven system, I just force the currents and
it doesn't particularly matter exactly how the 
antennas are tuned.

Rick N6RK

> Has anyone played with a 3-element vertical wire yagi, (electrically
> rotated) centered around a common point?
> (no rotor)
> IE: something resembling this (birds eye view) :
>                   .        .
>                       .
>                   .        .
> The center dot being a 1/4WL element. Each outside element (I'm thinking)
> could be the length of a reflector
> but with a small coil or linearly loaded piece of wire at the 
> bottom, which
> could be shorted by a simple SPST relay,
> ensuring it was then short enough to be a director.
> Mike VE9Antenna Antenna

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