Polarization and satellites positions (1 Viewer)

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al_madhi

SatelliteGuys Family
Feb 6, 2005
81
0
Riyadh - Saudi Arabia
Hi guys , could anyboy explain to me technicaly what is the relation between the polarization and the satellites posions , ( regarding to the rule that the polarization depends on the difference between the geographical longitude of the receiving site and the orbial position of the satellite . ) .

Any thoughts you would have be greatly appreciated .


Best Regards

A.M.AL-Madhi
 
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zamar23

SatelliteGuys Pro
Feb 5, 2009
1,204
1
Mid West
It looks like you're asking why do we have to skew the dish? As I visualize it in 2-and-3d, the more a sat is east or west from your location, the bigger its signal direction angle is, while polarization direction remains the same, so a dish or LNB should follow both angles. It allows the dish to receive the signal at angle reflectable towards its focal point, and properly polarized when hitting the LNB.
 

al_madhi

SatelliteGuys Family
Feb 6, 2005
81
0
Riyadh - Saudi Arabia
It looks like you're asking why do we have to skew the dish? As I visualize it in 2-and-3d, the more a sat is east or west from your location, the bigger its signal direction angle is, while polarization direction remains the same, so a dish or LNB should follow both angles. It allows the dish to receive the signal at angle reflectable towards its focal point, and properly polarized when hitting the LNB.
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Thanks zamar23 for responding to my thread . It seem to me that you only understood 50% of my question - the question is about Polarization Rule which is related to the goegraphical longitute dish site on the ground and the orbital location of the satellite . Please read the question again and concentrate on the Polarization Rule .

Best Regards

A.M.AL-Madhi
 

B.J.

SatelliteGuys Pro
Oct 15, 2008
2,029
1
Western Maine
Hi guys , could anyboy explain to me technicaly what is the relation between the polarization and the satellites posions , ( regarding to the rule that the polarization depends on the difference between the geographical longitude of the receiving site and the orbial position of the satellite . ) .

Any thoughts you would have be greatly appreciated .


Best Regards

A.M.AL-Madhi

Well, it's too complicated a relationship for my aging brain to figure out quickly, but I will say that it's dependent on more than the difference in longitude, ie particularly latitude affects it greatly. For example, consider that at the equator, basically all satellites have a 90 deg skew, independent of the longitude difference. And if you could see geostationary sats from the north pole (you can't), all sats would have 0.0 deg skew, again independent of the longitude difference.
In any event, it's not just a simple relationship relative to longitude difference. Not an exact relationship, but a very crude approximation is to subtract your latitude from 90 deg, and multiply this times the SIN of your USALS angle to the sat, which is a bit bigger than the delta longitude. This comes within a couple degrees in most cases I've tried, but I think to get an exact number would require some rotation of coordinates, which I'm not very good at (I can do it, but it takes a whole afternoon of thinking, and I'm getting too old to think that much :) ).
 
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zamar23

SatelliteGuys Pro
Feb 5, 2009
1,204
1
Mid West
Please read the question again and concentrate on the Polarization Rule.
I'm not used to think at all, and its hard for me to concentrate on something, but to visualize a bit more, to see the strongest signal, one's dish needs to look underneath the right antenna of a selected sat. To look underneath from far right or left location on Earth compare to the sat on the Equator, the dish needs to turn its head left or right and screw it opposite the clock or following it. If you're on the same Long. with the sat - dish looks forward and up. Just like looking underneath of my old small Ponty - it all depends on where I'm looking from. But it doesn't want to run anyway, no matter how much I screw my head to look under it.
 
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