V_g = open circuit voltage of the generator

Z_g = antenna impedance

Z₀ = Characteristics impedance of the transmission line connecting generator to the antenna

P_inc = Incident power to the antenna terminal

P_refl = Power reflected from the antenna terminal

P_in = Input power to the antenna

X_A = Antenna reactance

R_e = Loss resistance of the antenna

R_r = Radiation resistance

Fig 7.6 (a) : Equivalent circuit of a T_x antenna