Case study 8
Repeat Case study 5 for 1% and 0.1% of worst month rainfall case in Canberra.
Solution 8
From case study 7 we know 1% worst month attenuation for Canberra is 0.59 dB
Similarly we also find 0.1% worst month attenuation for Canberra to be 2.37 dB
For 1% worst month rain attenuation the range of possible antennas may include:
Dish size gain 1.0 % WM rain cost Tsys type no (dBi) attenuation ($A requirement (dB) retail) (deg K) D1300 1.6 m 44 0.59 320 87 D1400 1.8 m 45 0.59 490 110 D1490 2.4 m 46.5 0.59 750 155 D1600 3.65 m 49.8 0.59 1890 332 D1700 5.0 m 51.2 0.59 4250 458
Similar calculations lead to :
Dish size gain cost TLNC LNC Noise Suggested Cost type (dBi) ($A requiremen Figure LNC ($A no retail) t (deg K) Requirement type retail) (dB) number D1300 1.6 m 44 320 -3 n/a n/a n/a D1400 1.8 m 45 490 20 0.3 n/a n/a D1490 2.3 m 46.5 750 64 0.85 L1200 260 D1600 3.65 m 49.8 1890 237 2.6 L1100 200 D1700 5.0 m 51.2 4250 360 3.5 L1100 200
Least cost solution is D1490 dish with L1200 LNC.
For 0.1% worst month rain attenuation the range of possible antennas may include:
Dish type size gain 0.1 % WM Rain cost Tsys no (dBi) attenuation ($A requirement (dB) retail) (deg K) D1490 2.3 m 46.5 2.37 750 103 D1600 3.65 m 49.8 2.37 1890 220 D1700 5.0 m 51.2 2.37 4250 304
Similar calculations lead to :
Dish size gain cost TLNC LNC Noise Suggested Cost type (dBi) ($A requirement Figure LNC type ($A no retail) (deg K) Requirement number retail) (dB) D1490 2.3 m 46.5 750 - - n/a n/a D1600 3.65 m 49.8 1890 53 0.7 L1200 260 D1700 5.0 m 51.2 4250 135 1.7 L1100 200
Least cost solution is D1600 dish and L1200 LNC.
A solution for the 0.1% W.M. case is not possible because the increased rain attenuation (and to a lesser extent antenna noise temperature) put the system requirement out of the range that can be provided even with a 4.6 m earth station.
Return to Case Study Index
Return to Index