[MLB-WIRELESS] Orientation of antennas

[Matt Pearce]

For all those antenna guru's out there can you tell me how hard would it be
to copy Ryan's antenna ??  It looks fairly simple in design but never having
made one I cant guess at this.

Matt.


----- Original Message -----
From: "Ryan Abbenhuys" <sneeze at alphalink.com.au>
To: <melbwireless at wireless.org.au>
Sent: Monday, July 15, 2002 6:42 PM
Subject: Re: [MLB-WIRELESS] Orientation of antennas


> Ahhhh, thankyou very much donkeydick.
>
> The antenna i'm using is one of these
> http://www.alphalink.com.au/~sneeze/pics/antenna.jpg
> So taking in what you have said I can see exactly why the signal was so
bad!
>
> I was pretty sure it would be obvious to one of you antenna geeks on here
> ;-)
>
> ----- Original Message -----
> From: "Jason Hecker" <jason at air.net.au>
> To: "Ryan Abbenhuys" <sneeze at alphalink.com.au>;
> <melbwireless at wireless.org.au>
> Sent: Monday, July 15, 2002 6:20 PM
> Subject: Re: [MLB-WIRELESS] Orientation of antennas
>
>
> > Ahhh,
> >
> > Grasshopper, you have not maintained the correct orientation of the
> > gridlines on the dish with the dipole.
> >
> > I remember at Questacon in Canberra years ago they had an experiment
where
> > some low power microwave radiation was vertically polarised and
> transmitted
> > to a receiver a few metres away.  You were given a flat metal grid with
> all
> > the grid lines going in one direction, there were no cross bracing grid
> > lines at all.  This was the polariser.  As you span it around, the power
> > level of the microwave was altered, letting through a proportionate
> > amount.  Have the grid 90 degrees to the orientation of the transmitted
> > signal and none got through (the representative tone would disappear).
> >
> > So yes, your ex-Galaxy antenna's grid must be aligned the same as the
> > dipole, else forget it actually reflecting anything, it'll just let most
> of
> > the signal pass right through it.
> >
> >
> >
> > At 06:01 PM 15/07/2002 +1000, Ryan Abbenhuys wrote:
> > >I have an antenna orientation question too.....not quite as dumb I hope
> ;-p
> > >
> > >Okay, the waveguide on my AP is horizontally polarised, so of course if
> > >you're connecting with a galaxy or similar dish you have to swing it
> around
> > >90 degrees from the usual orientation.  However, one of my client
> > >connections is using one of my commercial 24's, which allows you to
just
> > >spin the dipole 90 degrees instead of the whole dish, thus you get the
> full
> > >use of the adjustments on the dish mounts.
> > >.....however, after putting up with a mysterious shite signal for a few
> > >months I pulled it down to try something else, span the dipole back to
> the
> > >original orientation and instead spun the whole dish........and whola!!
> > >Connection jumps from something like -85 to -70.
> > >So my question is, does the reflector itself somehow have an effect on
> the
> > >polarisation??  I thought it was just the dipole itself?
> >
>
>
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