Explain different orbital parameters in satellite communication

Q] Explain different orbital parameters. [5 Marks]

Answer: Orbital elements of the satellite are the parameters required to uniquely identify a specific orbit. In astronomy and orbital mechanics there are overall six parameters used to define an orbit. These are:

1. Semi-major axis:As per kepler's law when satellite traces an earth in an elliptical orbit we get major and minor axes of an ellipse. Semi-major axis is half of the length of orbits major axis and denoted by 'a'.
   
2. Eccentricity:The eccentricity of an elliptical orbit describes, how an elliptical orbit is different from the circular orbit. Eccentricity is related with radius vectors of apogee and perigee points over elliptical orbit. It is denoted by 'e'.
   
   r_a = apogee radius vector
   r_p = perigee radius vector
3. Argument of perigee: It is the angle made between line of nodes (a line which connects ascending node to descending node) and a line which connects perigee point to the center of earth. It is denoted by 'θ'.
4. Angle of Inclination: It is angle made between equitorial orbit to the inclined elliptical orbit of the satellite. It is denoted by 'i'.
5. True anomaly: It is the angle made at the center of earth by radius vector connecting directly tthe position of satellite in elliptcal orbit. It is denoted by 'Ω'.
6. Right Ascension of Ascending Node (RAAN): The longitude of ascending node is also known as right ascending node is also known as right ascension of ascending node or simply RAAN denoted as angle 'γ'.