2.Calculation of Transmit antenna gain  

1. Antenna diameter: Diameter of parabolic reflector antenna is referred as antenna diameter. It is denoted by ‘D’ 

2. Antenna efficiency: Antenna efficiency is the ratio of input power to the radiated power of the antenna. It is denoted by 'h'. The value of ‘h’ lice between 0.55 to 0.73.

3.Antenna gain G_T: The isotropic power gain of the antenna, G_T, is defined as the power density in the maximum direction, denoted here by P_D,to the power density archived by a 100% efficient isotropic radiator.

Thus

                           P_T is the total power radiated.
         Antenna gain in G_T  = 10 log (p²D²h/(l²*100))
                                            = 10 log (p²D²h/((C/f)²*100))
                                             =10 log (p²D²h/((3/10*f)²*100))
                                             =10 log (p²D²h/(3/f)²)……………(dB)………..[2]