Azimuth and Elevation Angle for Satellite tracking

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Azimuth (Az)

The earth station needs to know where the satellite is in the orbit. Then the earth station engineer needs to calculate some angles to track the satellite correctly. These angles are called antenna look angle. The look angles for the ground station antenna are the azimuth and elevation angles required at the antenna so that it points directly at the satellite. With the geostationary orbit the situation is much simpler than any other orbit. As the antenna beam width is very narrow and tracking mechanism is required to compensate for the movement of the satellite about the nominal geostationary position. Three pieces of information that are needed to determine the look angles for the geostationary orbit are

a. Earth station latitude
b. Earth station longitude
c. Satellite orbital position
Using these information antenna look angle can be calculated using Napier’s rule (solving spherical triangle). Azimuth angle denotes the horizontal angle measured at the earth station antenna to north pole. Elevation is such angle denotes the vertical angle measured at the earth station antenna end from ground to satellite position.

Figure : Antenna azimuth angle
Equation for Azimuth (Az) determination

Here G = Difference between satellite orbital position and earth station antenna.
          L = Latitude of your earth station antenna. 



Elevation (El)
In the above picture Az means azimuth angle required to track the satellite horizontally. In the figure below the elevation angle has been shown.
 
Figure : Antenna elevation angle



Equation for Elevation (El) determination

Here 0.1512 is constant
Note
1) If the satellite orbital location is in east (E), then G = Antenna longitude  - Satellite orbital position.
2) If the satellite orbital location is in West (W), then G = Satellite orbital position - Antenna longitude

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