Example For Calculation Of Look Angles

Example

Determine the look angles and the range for the situation given below.

latitude of the earth station (l_E)=-20 deg Longitude of earth station (f_E)=-30 deg, Longitude of sub satellite point f_s=+30 deg; height = 35,786 km radiuses of earth = 6378.14 km.

Solution:

_E=-20 deg

l_E=-30 deg

f_s=+30 deg

Height = 35,786 km

Radius of earth = 6378.14 km.

From the equation

B = - 30 - (+30) =-60^°

From the equation;

= -tan |-60|/sin(-20)

tan 60/sin20

= 5.064

A = tan^-15.064

Azimuth angle AZ=78.83 deg.

From the equation

Cos c = cos(-60) cos (-20)

=o.4698

and therefore sin c =0.8827

R_E + h =42164.14 km

d = squrt(6375.64²+42,164.14²-2*6375.64 *42,164.14*0.4698)

= 39,571 km

From the equation

= 42.164.14 * 0.8827 / 39,571

= 0.9405 and therefore

Elevation angle EI =18.86 deg.