Separation will depend on the antenna but I think typically a wavelength
should be enough. I had 2 11 element log periodic for some time
vertically polarized at 11 feet separation. The other guys here with
the same antenna system but 4 arrays had something like 11 feet vertical
as well. Those were homebrew antennas but remarkable performers. Alas
a guy wire failed in a microburst which ended their usefulness. We had
calculated their gain as about 18 dbi.
-----
BRETT WINCHESTER
[log in to unmask]
208-639-8386
###
-----Original Message-----
From: For blind ham radio operators
[mailto:[log in to unmask]] On Behalf Of Jerry Neufeld
Sent: Monday, May 21, 2007 3:15 PM
To: [log in to unmask]
Subject: Re: Stacked arrays on VHF & UHF
Steve,
Thank you much for this. The first thing I'll do is contact CushCraft to
see if they have any words or hardware appropriate to the twin anntennas
of theirs I have.
Good of you to write.
Jerry
----- Original Message -----
From: "Steve" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, May 21, 2007 2:59 PM
Subject: Re: Stacked arrays on VHF & UHF
> Jerry,
>
> I have experienced with baying arrays, which is horizontally split,
but
> not
> vertically stacking them. I can also tell you of a setup I had years
ago.
>
> First, as far as the two antennas. You'll need a phasing kit which
> consists of
> a T-connector and two lengths of 75-ohm cable to match the two
antennas as
> they
> will be fed in parallel. I don't remember the length of the phasing
> cables, but
> you can get them already mead up as part of a separation kit from
> Cushcraft.
>
> The other thing you need to consider is the phasing of your
transmissions.
> It
> used to be that the birds were left-hand circular polarized, if I
remember
> correctly. SSB is horizontal, and FM is vertical. Which mode will
you
> use the
> most? If satellite, then you need to circularly polarize it if that
is
> still
> necessary for the newer birds. My experience if from Oscar 13 days.
>
> A second consideration is that if you phase your two antennas, you
will be
> narrowing the beam width. That will mean that you might need to track
> them more
> precisely.
>
> Some thirty years ago, a brilliant friend of mine, Wa8LMF, came up
with
> the idea
> that I could put up a pair of 8-el HyGain two-meter beams and phase
them
> either
> vertically, horizontally, or righthand or lefthand circular as my
> operating mode
> changed. The way we did this was to put one beam up oriented with the
> elements
> going from upper left to lower right. The lefthand beam on the
horizontal
> boom
> had its elements going from upper right to lower left. The two
feedlines
> entered the shack and fed a T connector to the rig. If I wanted to
change
> the
> phasing, I inserted either a quarter wave in the left or right
feedline
> for
> circular polarization if I recall, or a half-wave phasing line in one
side
> to
> switch to horizontal polarization.
>
> I do know this much. If you worked FM and switched it to horizontal
> polarization, you had a considerable drop in signal strength. And,
when
> talking
> with an FM station, running circular polarization seemed to reduce the
> amount of
> picket fencing.
>
> Steve, K8SP
> ----- Original Message -----
> From: "Jerry Neufeld" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Monday, May 21, 2007 2:21 PM
> Subject: Stacked arrays on VHF & UHF
>
>
> I have 2 CushCraft dual-band, 5-element yaggies for VHF & UHF that I'd
> like
> to use for satellite work. Does anyone have any experience with
stacked
> arrays of this type? Any ideas where I might obtain accessible
material on
> how to optimize stacked, dual-band antennas? Any suggestions on this
would
> be much appreciated.
>
> Also, I have a MFJ antenna analyzer, the 269 to be specific. Although
this
> analyzer provides for UHF measurements, it does not have a pick-off
for RF
> which I need for my MCount morse-code frequency reader. Anyone have
any
> ideas on how I might gain access to the RF output of the analyzer
without
> significantly influencing readings, especially for UHF?
>
> Thanks to anyone who has advice on these matters.
>
> Jerry VE3QSO
>
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