Re: [amsat-bb] AO-40 " BBQ " dish versus Primestar Dish ??

[Jon Ogden <na9d@xxxxxxxxxxxxx>]

Hey Jeff,

In hopefully another month or so, I'll be able to tell you for sure!  
I've been using a BBQ dish and it's done an "adequate" job for AO-40 
(please, no more BBQ wars people).  But I do want to have a better dish 
so I obtained a P*.  It is definitely bigger than the BBQ.  Take the 
few extra inches per side and calculate the area of the ellipse of the 
P* compared to the area of the BBQ and you'll see the P* is a good bit 
larger.  Then throw in the increased gain from going from a linearly 
polarized feed to a CP feed.  And finally, the feed itself with a helix 
is going to give better pattern performance (less spillover, etc.) than 
the dipole feed of the BBQ.  Most people mount their BBQs in the 
vertical direction (ie: horizontally polarized).  This is supposed to 
give better performance on AO-40.  But I've heard that thermal noise 
rising from the ground is also horizontally polarized and with the 
antenna pointing skyward, the feed is looking at the ground and picking 
up that noise.

I'll certainly let everyone know my results after I get a chance to get 
my new antenna up.

73,

Jon
NA9D

On Saturday, May 31, 2003, at 02:50 America/Chicago, K7XQ wrote:

> I am looking at the size difference between the BBQ dish and the
> Primestar dish.
> Does the slightly larger size of the Primestar Dish REALLY make a
> difference on the AO-40 downlink ???

----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org