Probability distributions had been used to characterize electric field intensity. In this study, Birnbaum-Saunders (B-S) and Generalized Birnbaum-Saunders (GB-S) distributions were used to model the behavior of electric field intensity within the coverage area of broadcasting radio transmitter. Usually, the availability and usefulness of the signal at the primary and secondary coverage areas are guaranteed unlike at the fringe. The electric field intensity was measured with the aids of field intensity meter and global positioning system along some routes starting from the transmitting site to region where the signal becomes intelligible to the measuring device. The Probability Density Function (PDF) of the data was fitted with B-S and GB-S distributions. The parameters, mean, variance, skewness and kurtosis of the distributions were determined and compared. The result shows that the curves of B-S and GB-S distributions are both positively skewed and unimodal. The shape of the curves represents signal intensity which reduces from maximum at the primary to minimum at the fringe. The analysis yields shape ? and scale ? parameters of 1.945 and 1.434 for B-S distribution, 2.133 and 1.229 for GB-S distribution. A new exponent v of 0.033 was also generated for GB-S. The mean ?, variance ?^2, skewness ? and kurtosis ? are 3.945, 44.567, 3.377 and 19.097 for B-S distribution and 3.744, 45.954, 0.213 and 20.708 for GB-S distribution. With minimum difference, B-S and GB-S distributions modelled the attenuation of the signal as it propagates from primary across secondary to fringe where it becomes unreliable and intelligible.

Keywords: Birnbaum-Saunders distribution, Coverage Area, shape and scale parameters