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  7.Calculation of Downlink path loss  

1.Down Link frequency   Down link frequency is frequency at which satellite is communicating with ground station. For C band  up link frequency is in the order of  4 G Hz , 12 G Hz for Ku band. 

2.Downlink path loss  Down link  path loss depend on up link frequency & distance between satellite and ground station.
                              Down link loss=10 log(4pd/(C/f))2 
         Here
                                                        ‘d’ is the distance between satellite & ground station
                                                        ‘f’ is the frequency of the down link wave
                                                        ‘C’ is the velocity of the light = 3 x108 m/Sec
                             Down link loss = 20 log (4pd/(3/10*f)………(dB)………………[11]
                              Here            f is in Giga  hertz     

Example : calculate downlink path loss for the satellite located 37000 km far from the earth station and operating 3,950 GHz  frequency
                             Down link loss = 20 log (4pd/(3/10*f)
                                                    = 195.73 dB

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