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Fig. 2.1: Rain zone map, based on Rec.ITU-R PN.837-1
Rain attenuation can be calculated using ITU-R outage model, which consists of the following:
Obtain the rain rate R
0.01
exceeded for 0.01 per cent of the time (with an integration time of 1 min).
R
0.01
values are defined for 15 rain zones and different time percentages and they are given in ITU-R
Recommendation P.837.
Tab. 2.1: Rain rate R (mm/h) ITU-R P.837
Q P N M L K J H G F E D C B A
Percentage
of time (%)
14 12 5 4 2 15 8 2 3 1.7 0.6 2.1 0.7 0.5 <0.1 1.0
49 34 15 11 7 42 13 4 7 4.5 2.4 4.5 2.8 2 0.8 0.3
72 65 35 22 15 12 20 10 12 8 6 8 5 3 2 0.1
96 105 65 40 33 23 28 18 20 15 12 13 9 6 5 0.03
115 145 95 63 60 42 35 32 30 28 22 19 15 12 8 0.01
142 200 140 95 105 70 45 55 45 54 41 29 26 21 14 0.003
170 250 180 120 150 100 55 83 65 78 70 42 42 32 22 0.001
Compute specific attenuation γ
R
(dB/km) for the frequency, polarization, specific rain rate using ITU-R
recommendation P.838. Rain attenuation for rain rate γ
R
0.01
can be calculated as follows:
γ
R
0.01
= k
h,v
.R
0.01
α
h,v
where:
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Implementation Notes