Re: [amsat-bb] Offset Dish Antenna Aiming

[Bruce Bostwick <lihan161051@xxxxxxxxxxxxx>]

On Thursday, July 25, 2002, at 11:24 AM, Frederick M. Spinner wrote:

> Even thought it looks bizarre, many dishes can be turned upside down 
> (feed arm at the top) to get them to operate down to 0 degrees.
>
> It depends on your dish.  I think it does work for both the PrimeStar's 
> out there and the DSS/Dish Network dishes.  But I could be wrong on the 
> DSS dishes.
>
> Otherwise making a block of wood that is 22.5 degrees in angle and 
> mounting the dish to that and the block to the rotor can also correct 
> for the offset angle.

Only if the feed doesn't overilluminate the dish too much.  If your feed 
sees a large amount of area behind the dish, the ground or roof behind 
the dish will raise your noise figure ..

I did think of this for a mobile satellite application, because the 
offset dish in "birdbath" position is just about the right elevation for 
my latitude and has substantially less inclination to act like a sail at 
highway speeds, so it can be left deployed on the road ..

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