# Antenna pointing equations



## HIPAR (May 15, 2005)

Can someone provide the equations that define the Az and El pointing angles to a DBS. I have seen them on the internet but can't find them again.

I want to write my own software to solve the pointing problem.

--- CHAS


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## in0cul4t1on (Sep 25, 2005)

test


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## in0cul4t1on (Sep 25, 2005)

Sorry about the previous post. Im a new member so I had to make 5 posts before I could post a link. 
Hope those helps.

http://www.bigdish.info/mainten/align.html


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## HIPAR (May 15, 2005)

Thank you. That's what I need to start coding.

--- CHAS


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## kenglish (Oct 2, 2004)

You might also want to find the formula for computing the polarization angle. It's not important for the polarization in DBS, which is circular, but it is in linear-polarized sats. And, by interpolating the polarization angles between two birds, you get what the DBS companies call "skew", for multifeed dishes (like the DISH500, etc).

Wish I knew where that formula was.


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## HIPAR (May 15, 2005)

A least one person 'out there' will be interested in this.

I found an equation for polarization skew coded in Java:

http://www.arachnoid.com/satfinder/

I translated it to Borland Pascal as follows:

function ComputeSkew(RecLat, RecLon, SatLon: Double): Double;
var
dlngr: Double;
begin
dlngr := SatLon-RecLon;
Result := ArcTan2(Tan(RecLat), Sin(dlngr))-pi/2;
end;

The inputs and result are in radians. Satellite and receiver longitudes are negative in the western hemisphere. If you are into programming, you will know what that means.

I have not tested it rigorously, but the results seem to agree with calculators available on the Web.

--- CHAS


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