Methods for determining dish antenna pointing angles

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Virginia Tech


Satellite Look Angles are the coordinates to which an earth station antenna must point to communicate with a satellite. Each satellite has it's own unique set of look angles. The first method, developed to calculate a satellite's look angles, uses standard plane and spherical trigonometry and assumes a perfectly spherical earth. The second method developed is unique to this paper and wi11 not be found anywhere, including general satellite communication textbooks. This method uses a geodetic reference system which refers to the earth as an ellipsoid rather than a sphere. This second method is a more rigorous approach to determining look angles and readily lends itself to pointing at satellites in any given orbit. Fortran code was written implementing both methods and it is concluded that employing a geodetic reference frame is viable where high degrees of accuracy are required. Fortran code was also developed to calculate the pointing angles for Radio Sources such as pulsars and quasars. This code corrects for precession, nutation, annual aberration, and polar motion of the earth.