Re: [amsat-bb] Dish aiming

["Bill Jones" <wejones@xxxxxxxxxxxx>]

> > Seems like lots of folks have high hopes for the microwave parts of P3D.
> > BUT ... are the average rotators/elevators sufficiently accurate to use
> > with the narrow beamwidth of dishes etc ?
> 
> My Yaesu AZ/EL was far more than adequate for manual and computer aiming of
> my 4.5' dish on Mode S with AO-13...
> Photos at: http://vulcan.com/n4nrsat.htm
 
There is a big difference between mode S on AO-13 and some of the  freqs 
planned for P3D.  On 2.4 GHz, a 4.5 foot dish has a resolution of somewhere 
between 5.5 and 6.5 degrees, depending on how it is calculated.  As the 
frequency goes up, the resolution narrows.  On the 24 GHz freq planned on 
P3D, that same 4.5' dish has a resolution one tenth of that, down around 0.6 
degrees.   So it depends on what frequency you plan to to work, and at what 
gain (dish size).   I think there would indeed be a problem with a standard 
AZ/EL rotator if you try to use a lot of gain, but with the higher freqs you 
don't need such a big dish to get reasonable gain, so you can use a smaller 
dish or other antenna with wider beam width.  Ie more gain is not always 
better.  


**************************************
*Bill Jones  N3JLQ  Sweden Maine     *
* wejones@megalink.net               *
* http://www.megalink.net/~wejones   *
**************************************
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