Reflector skew signal loss

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Joe DC

SatelliteGuys Family
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Aug 19, 2011
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Cana,Va
On a fixed oval shape offset Ku dish designed for a single LNB would there be signal loss if only the LNB is skewed and not the dish? For skews 45 degrees or more it would seem that the dish illumination pattern would be partially off the dish thereby reducing the signal level. If so would the signal loss be significant?
 
nope. Dish illumination isn't decreased. The illumination shape is a cone. And the surface it's (the feed horn/lnbf) looking at is a perfect circle.
To 'see' this. Remove the LNBF. look at the dish face from the LNBF's perspective. (eye 'in' the feed holder)
From the satellites perspective, it's also a perfect circle.
 
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This could be proper if you are using a single regular off-set dish with an added sidecar lnb to aim at two satellites at once, BUT don't skew the dish itself to follow the arc. That's why multi-sat dishes are elliptical, so the dish can be skewed and fully (or as close as can be done) illuminate all lnb's to maximum dish surface.
 
So the LNB sees a circle within the dish no matter what the skew. Thanks for clarifying.
 
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