Re: [amsat-bb] Getting more gain without a solid dish.... -idea 2.

[Al Lawler <alawler@xxxxxxxxxxxxx>]

  Hi Stan (and others),

  The general consensus seems to be that this will only
work if the 2 converters are phase-matched, which is 
difficult.

  I'm wondering if it would make more sense to just
use a 2.4ghz phasing harness between the dual preamps
but before the (single) converter?



  -al



Stan wrote:
> 
> Hello Al,
> 
> Sounds like a good idea.
> 
> Considerations:
> 
>         would work best if both feeds, fed lines, converters were
>         amplitude matched AND phase matched.
> 
>         Probably the interaction between 2 orthogonal feeds would
>         be at a minimum. Reactive near field and near field
>         considerations.
> 
>         I guess one would be mounted 3' x 2' with the 3' being
>         vertical and the other would be mounted 2' x 3' with the
>         2' being vertical, for a minimum of 5' wide x 3' max height.
>         Still a lot of wind /ice loading area.
> 
> I would like to hear of your test results.
> 
> Stan, WA1ECF  FN41   Cape Cod, MA
> 
> Al Lawler wrote:
> >
> >   After my first night on ao-40,  I can see that
> > despite not being the "poorest kid on the block"
> > recieve-wise, I could definately do with some
> > more antenna gain.
> >
> >   My current setup is a 24dbi(linear) gain bbq
> > dish with a DEM preamp and drake converter with
> > the easy mods.
> >
> >   Using the Ao-40 spreadsheet, I see that the
> > only thing I can really benifit from improving
> > is the antenna itself.  (And possibly a few db
> > more preamp gain, but not much.)
> >
> >   Going to a solid dish with a helix feed isn't
> > an option, due to wind/snow  resistance and weight
> > considerations.
> >
> >   What I'm thinking of doing is to simply add
> > a second BBQ dish, cross polarized with respect
> > to the first one), with its own preamp/converter
> > (another dem/drake), then connecting the (144mhz)
> > outputs of both drakes to the feedline via  a 2-meter
> > "circular" phasing harness.  (I.e. the same
> > harness used to get circular polarization out of
> > 2 yagi's.)  The idea is to be able to generate
> > a circularly polarized antenna (with more capture
> > area), without having to manufacture a precision
> > phasing harness for 13cm.
> >
> >   Does anybody have any comments on how well this
> > is likely to work?
> >
> >   -al
> > ----
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