C-Band Dish Signal Angles

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Babadem

Babadem

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May 21, 2007
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Can someone explain to me how a C-Band Dish/LNB (Prime Focus) receives a satellite signal as compared to a KU Band offset Dish/LNB. I'm contemplating on taking advantage of the $69.99 C-Band Sale by Robbie from WSI and I have limited space. Understanding the C-band reception process will help me decide. Any diagrams or illustrations will be highly appreciated.
 
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brex2001

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Jul 14, 2009
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parabolic reflectors

From my understanding of prime focus reflectors, the focus point is along the central axis line of the paraboloid. A plane perpendicular to the axis of the paraboloid defines the shape.

The shape of offset reflectors are defined by a plane to an angle of 22 to 27 degrees to the axis line of a paraboloid. The focal point is still along the central axis of the paraboloid.

Here are some diagrams, pdf & .doc files to help illustrate these 2 types.
It's not a lot of info, but it's a start.

:)
 

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Anole

Anole

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Sep 22, 2005
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one green guys opinion:

The Geo-Orbit site may have more detailed info than you want.
But, if you would scan through the pictures on its three or four pages, then read the relevant text, I think it might be helpful.
It's where I got my initial understanding of BUDs.

The declination is not as big a deal as you might think, so don't let that scare you off.

Lastly, let me put in a plug for the DMX242 dual-output LNBF.
The two independent outputs will come in handy eventually, and I'd never get locked into a single again.
Likewise, the dual-band LNBFs are hard to aim for Ku; most of us are better off with a separate 1m Ku dish.
 
Babadem

Babadem

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Let's assume there is a slight LOS issues, how will the Prime focus perform in relation to an offset dish?
 
Anole

Anole

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Sep 22, 2005
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LOS is LOS.
What the dish can see is what it can see.
The difference is the prime focus dish will -appear- to be aimed about 25° higher than a similar offset, but both will actually -see- the same bird.
(if aimed at it) - :rolleyes:
 
SatelliteAV

SatelliteAV

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Sep 3, 2004
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Babadem said:
Let's assume there is a slight LOS issues, how will the Prime focus perform in relation to an offset dish?

There must be direct line of site without obstruction. No difference as both dish types receive the satellite signal from the same point in the sky.

Edit... Anole beat me to the send button!!!!
 
Babadem

Babadem

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May 21, 2007
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The Geo-Orbit site may have more detailed info than you want.
But, if you would scan through the pictures on its three or four pages, then read the relevant text, I think it might be helpful.
It's where I got my initial understanding of BUDs.

The declination is not as big a deal as you might think, so don't let that scare you off.

Lastly, let me put in a plug for the DMX242 dual-output LNBF.
The two independent outputs will come in handy eventually, and I'd never get locked into a single again.
Likewise, the dual-band LNBFs are hard to aim for Ku; most of us are better off with a separate 1m Ku dish.
Thanks, Anole! I just got the DMX 242 about 3 weeks ago, plus I have GEOSATpro C2 ,which I'm currently using on my Mini-BUD, and I know what you mean by having the dual independent output present in any LNBf. They're great. I also have the Single DMX741U C/KU combo. I believe you know how that fares with KU signal without user Modification.:rolleyes:
 
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Anole

Anole

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Sep 22, 2005
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L.A., Calif.
Well, I have a bunch of C2's myself, but from what I can tell, both they and the 242 work very well. - :up
And I'm just a strong supporter of having two outputs...
... if not for two receivers, then for that multiswitch you'll eventually want to hook to it! - :cool:
(and for whatever small price difference over single output, why bother?)
 
Babadem

Babadem

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May 21, 2007
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Let's assume there is a slight LOS issues, how will the Prime focus perform in relation to an offset dish?

LOS is LOS.
What the dish can see is what it can see.
The difference is the prime focus dish will -appear- to be aimed about 25° higher than a similar offset, but both will actually -see- the same bird.
(if aimed at it) - :rolleyes:
Thanks, Guys for your responses.
 
Babadem

Babadem

Thread Starter
SatelliteGuys Pro
May 21, 2007
2,294
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MA
From my understanding of prime focus reflectors, the focus point is along the central axis line of the paraboloid. A plane perpendicular to the axis of the paraboloid defines the shape.

The shape of offset reflectors are defined by a plane to an angle of 22 to 27 degrees to the axis line of a paraboloid. The focal point is still along the central axis of the paraboloid.

Here are some diagrams, pdf & .doc files to help illustrate these 2 types.
It's not a lot of info, but it's a start.

:)
Thank you for your insight.:up:D
 
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