
Calculator normalises all distances to kilometers and meters

Miles to Kilometers = 1.609

Kilometers to miles = 0.621

feet to meters = .3048

meters to feet = 3.28

1st Fresnel Zone radius (Km) = 17.3 x Sqr root ((Obstacle Distance x (Total Link  Obstacle Distance)) / (Frequency in GHz x Total Link))

1st Fresnel Zone radius (miles) = 72.6 x Sqr root ((Obstacle Distance x (Total Link  Obstacle Distance)) / (Frequency in GHz x Total Link))

Obstacle free radius = 0.6 x 1st Fresnel Zone radius

Radius of nth Fresnel zone (meter) = sqr root ( (n x wave length x Obstacle distance x (Total Link  Obstacle Distance)) / Total Link )

wave length (meters) = speed of light (299,792,458 m/s) / frequency in Hz

Earth curvature calculation = (Total Link) ^{2} /(8 * effective earth radius)

effective earth radius = 4/3 * Earth radius

Earth radius = 3963 miles, 6378 Km