Radiocommunications Advisory Guidelines (Co-ordinating the operation of transmitters in the 500 MHz Bands)
2. Single rounded obstacle2. Single rounded obstacle
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2. Single rounded obstacle
Lt = J() + T(m,n)
where:
J() = single knife-edge obstacle loss calculated in 1. above.
T(m,n) = is the additional attenuation due to the curvature of the obstacle.
= 7.2 m1/2 - (2 - 12.5 n) m + 3.6 m3/2 -0.8 m2 for mn 4
= -6 - 20 log(mn) + 7.2 m1/2 - (2 - 17n)m + 3.6 m3/2 - 0.8 m2 for mn 4
where:
m = R ((d1 + d2)/d1 d2) / ( R /)1/3
n = h ( R /)2/3 / R
R = radius of a rounded obstacle (km)
d = length of path (km)
d1 and d2 = distances of the two ends of the path from the top of the obstacle (km)
h = height from the top of the obstacle (ho) to the straight line joining the two ends of the path. If the obstacle is below this line, h is negative. (m)
ho = fixed terrain height of obstacle (m) + terrain height correction due to k-factor (m). (k=3 which represents > 20% of time)
= (d1 d2)/(12.75 k)
= wavelength (m)
- Double isolated edges
Use Recommendation ITU-R PN.526-3
- General method for one or more obstacles
Use Recommendation ITU-R PN.526-3