Radiocommunications Advisory Guidelines (Co-ordinating the operation of transmitters in the 500 MHz Bands)
1. Single knife-edge obstacle1. Single knife-edge obstacle
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1. Single knife-edge obstacle
= 0.0316 h ( (2 / ) (d1 + d2) / d1 d2)1/2
where:
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)
For greater than -0.7 an approximate value can be obtained from the expression:
Lt = 6.9 + 20 log((( - 0.1)2 +1) + - 0.1)