RE: [amsat-bb] Dual Dipoles for Echo?

[David Rush <david@xxxxxxxxxxxxxx>]

Al:

I'd thought about that (higher gain omnis - flattening the donut), but not 
any specific designs.

Another person suggested Lindenblads.  I built a 2m and 70cm set a few 
years ago, but they're long since gone.  Not so good for the overhead 
passes, I would think.

David

At 04:15 PM 11/15/2004, alan_bloom@agilent.com wrote:
>Why not use a gain-type omnidirectional antenna like a collinear?  (Often 
>used for repeaters or home stations)  You could still tilt it so the 
>radiation pattern "donut" tracks the arc of the satellite's path.
>
>Al N1AL
>
> > -----Original Message-----
> > From: owner-AMSAT-BB@amsat.org [mailto:owner-AMSAT-BB@amsat.org]On
> > Behalf Of David Rush
> > Sent: Thursday, November 11, 2004 7:26 AM
> > To: amsat-bb@amsat.org
> > Subject: [amsat-bb] Dual Dipoles for Echo?
> >
> >
> > Dragging my Arrow antenna (with elements sticking out every direction) and
> > camera tripod out to work Echo, along with having to track it, is 
> getting a
> > bit old.  I've come up with the idea to build two simple dipoles (2m &
> > 70cm), mounted some distance apart on a piece of wood or Plexiglas, with
> > the elements parallel (Sort of a lop-sided H shape).
> >
> > In prep for a pass the thing would be oriented so the donut-shaped 
> patterns
> > would hit the arc of the satellite's path across the sky.
> >
> > Advantages: no re-aiming during the pass, and a bit more compact than the
> > Arrow, should work better than a vertical for high-elevation passes.
> > Disadvantages: lower gain than the Arrow.
> >
> > Any ideas how far apart the two dipoles should be?  The Arrow has them on
> > the same boom, but the driven elements are 20-30 cm apart and they're
> > polarized differently.
> >
> > Would there be an optimum distance off the ground each dipole should be in
> > order to take advantage of ground reflection?
> >
> > Any other thoughts on this?
> >
> > David, KY7DR
> > ----
----
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