SEAMCAT Handbook (pdf) - Cept

f: frequency (MHz).Note 1: The following approximation to the inverse complementary cumulative normal distribution function, Qi(x), isvalid for 0.01 x 0.99 :Q i (x) = T(x) –(x) if x 0.5Q i (x) = ‐{T(1‐x) – (1‐x)} if x > 0.5where:T(x) [ 2ln( x)][( C ( ) ) ( )]( )2 Tx C1Tx C x 0[( D3T( x) D2)T( x) D1] T( x)1C 0 = 2.515517C 1 = 0.802853C 2 = 0.010328D 1 = 1.432788D 2 = 0.189269D3 = 0.001308Note 2: the path length which just achieves a clearance of 0.6 of the first Fresnel zone over a smooth curved Earth, fora given frequency and antenna heights h t and h r , is given approximately by:D f DhD06D f Dhwhere:D f : frequency‐dependent term= 0.0000389f h1h2kmD h : asymptotic term defined by horizon distances= 4.1(ht hr)kmf: frequency (MHz)h t , h r : antenna heights above smooth Earth (m)In the above equations, the value of h t must be limited, if necessary, such that it is not less than zero. Moreover, theresulting values of D 06 must be limited, if necessary, such that it is not less than 0.001 km.Note 3: the case h t is less than zero described in the recommendation is not handled.Note 4: no correction due to terrain clearance angle is implemented.km200