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Low Elevation angle and Dish Offset Angle

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Ex Member
Ex Member


Dec 3rd, 2006 at 4:02am  
Hi, I am new here and would like to benefit from your experience.

Assuming 22-24 degrees as the standard offset angle for any given offset dish, how would I point my dish towards a satellite whose elevation angle at my location is 18 degrees? My dish would be looking down to the groud by 4-6 degrees. Is that acceptable? While scavenging through sites, I came across an interesting tip that the dish could be setup upside down -- in my case that would mean that my dish would be looking up by 22-28 degrees. If I fixed my dish upside down, would the arm holding the LNB come in the way of signals falling on to the dish?

Where I live, I get a lot of cheap 60-90 cm Ku band Dish. But they do not carry any technical specification as to the offset angle. Is there a way we can arrive at this figure approximately?

Thanks. Please bear with me if I have repeated the often-asked/repeated question.
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Ex Member
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Reply #1 - Dec 3rd, 2006 at 4:36am  
I would have assumed most offsets were closer to 17-18 degrees, but that's moot if we don't actually know the make/model of your hardware - where you live - and from which satellite you're attempting to intercept a signal.

It would also help to know if there is an EL scale on the antenna bracket, and - if so - whether or not the owner's manual indicates the scale already compensates for offset

//greg//
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« Last Edit: Dec 3rd, 2006 at 2:09pm by N/A »  
 
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Reply #2 - Dec 3rd, 2006 at 5:39am  
Hi,

Yes this looks like an interesting experience. I have come across a similar problem way back in the '90s. I remember to have adopted the method you suggested.

In the case of a boom-low installation, you actually subtract the offset angle from the elevation to arrive at the actual elevation angle. Based on the location, the elevation could be so low that may not really help receiving the satellite signal properly.

So, we go for boom-high installation, where the booms holding the feed horn will be at the top of the antenna structure. In this case, you have to add the offset angle to the elevation to arrive at the actual elevation angle. This type of installation really helps in situations of low elevation angles.

We used a 1.8M Offset Truncated Parabolic C-Band antenna. But, I am sure, based on the make / model this shall be possible with any other antennas.
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