Propagation Effects Handbook for Satellite Systems - DESCANSO ...

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The worst-month found to be closely versus annual probability relationship has approximated by a power law of the form been T= A~-$ (6.3-25) where Q is the ratio of the average worst-month probability to the average annual probability (Y) and A and ~ are coefficients. The observed ranges of coefficient values are 1.2 S A S 3.3 and 0.167 S ~, S 0.074 (CCIR Rep. 723-1, 1982a). A useful approximate relationship between worst-month exceedance time percentages (p ) and annual time percentages (p W) is (CCIR, 1982a): P = 0.29 PW 1+15 (6.3-26) where p and p v are in percent. The corresponding coefficient values for the previous power law relationship are A = 1.64 and ~ = 0.13. These values yielded Q ratios in good agreement with average values for different locations in North America and Europe. For current CCIR recommendations, the reader is referred to CCIR report 723-2, “Worst Month Statistics”, (CCIR, 1986e). 6.4 CLOUD, FOG, SAND AND DUST ATTENUATION 6.4.1 Specific Attenuation of Water Droplets The water droplets that constitute clouds and fog are generally smaller than about .01 cm in diameter. This allows the Rayleigh approximation to be used to calculate specific attenuation in clouds and fog for frequencies up to 100 GHz. Using this approximation, the specific attenuation ac is, unlike the case of rain, independent of the droplet size distribution. It is proportional to the liquid water content pf: aC = KCptdB/km (6.4-1) ptis normally expressed in units of g/ins. The attenuation constant KC is a function of frequency and temperature and is given by Figure 6.4.1 (CCIR Rpt. 721-1, 1982a). The curves given in the figure assume pure water droplets. The values for salt-water droplets, corresponding to ocean. fogs and mists~ are higher by approximately 25% at 20°C and 5% at O°C (Koester and Kosowsky-1978). 6-62
● ✎ ✎ ✎ 10 1 0.1 0.01 0 . ------ 1 1 I I I 1 I I I I 1 1 I I I 1 I Figure 6.4-1. Attenuation Coefficient Kc Due to Water Droplets (from CCIR 1982a, Rpt 721-1) 6-63 100 150
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1 6.1 INTRODUCTION 6.1.1 purpose CH
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,s Table 6.1-1. Guide to Sample Cal
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I . . 6.1.4 Other Propagation Effec
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. . collisions at normal atmospheri
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D 1000 100 10 1 U.S. Standard Atmos
Page 11 and 12: Frequency (GHz) 10 15 20 30 40 80 1
Page 13 and 14: If PW is not available from local w
Page 15 and 16: . . The equivalent heights for oxyg
Page 17 and 18: m t TEMPERATURE rC) o 5 10 15 20 25
Page 19 and 20: 6.3 PREDICTION OF CUMULATIVE STATIS
Page 21 and 22: LSTATION LOCATION AND ELEVATION STE
Page 23 and 24: The models require the following in
Page 25 and 26: I z za E 100 g w ~ z z K 50 a) ALL
Page 27 and 28: B . . . t- I I I I I 1 11/1 - . . .
Page 29 and 30: .- . 9 s@EQ - If Z S D, compute the
Page 31 and 32: 1 0.02 0.05 0.2 0.5 4. Compute D: U
Page 33 and 34: I . ,. . ~ q 8 H v ~ 1.0 0.8 0.6 0.
Page 35 and 36: Step 6 Calculate the attenuation ex
Page 37 and 38: m I : STEP 1 SELECT CLIMATE ZONE FR
Page 39 and 40: 9 10.OOOO 1.0000 0,1ooo 0.0100 0.00
Page 41 and 42: 1 6.3.3 Estimates of Attenuation Gi
Page 43 and 44: ● We now proceed exactly as in th
Page 45 and 46: STEP 1 GIVEN: STATION PARAMETERS SA
Page 47 and 48: . B . . . 4. Repeat the process for
Page 49 and 50: . . ● 100 10 1.0 .1 .01 . . RAIN
Page 51 and 52: not normally available~ but empiric
Page 53 and 54: ● The intensity-duration-frequenc
Page 55 and 56: - GIVEN: STATION PARAMETERS OPERATI
Page 57 and 58: m I s 70 2(J I 10 0 a) BY SEASONS
Page 59 and 60: .“ ● change in rain rater the r
Page 61: m To x o 6 x(n wux!- (5 zawwvxw x 1
Page 65 and 66: ● ✎ ✎ ✎ appears to be gener
Page 67 and 68: 6.4.2.3 Statistics of Microwave Eff
Page 69 and 70: ● For each hour’s observations,
Page 71 and 72: Plots of noise temperature and atte
Page 73 and 74: .- I where Lf is the fog extent~ in
Page 75 and 76: than a minute and on spatial scales
Page 77 and 78: . . . 022 = angle-of-arrival varian
Page 79 and 80: B . . Figure 6.5-2 represents the a
Page 81 and 82: - . . , 1 I t , 3 , I 1 # 1 1 aJ 0a
Page 83 and 84: I . . -. % i ! ~ * 76.00 I h 60.00
Page 85 and 86: I where the constants are the same
Page 87 and 88: .U . . \ Table 6.5-1. Fading Data P
Page 89 and 90: o -5C \ A — . \ \ \ \ N- ● ●
Page 91 and 92: I 1 \ 0,, FADE DEPTHS I 1 l.d 0.1 1
Page 93 and 94: 9 m ELEVATION ANGLE [DEGREESI ELEVA
Page 95 and 96: Figure 6.5-12 is an example for thi
Page 97 and 98: equal. The fade distributions resul
Page 99 and 100: m . ANTENNA BEAMVVID~ (DEG) d o 0 w
Page 101 and 102: . . 6.5.5.2.2 Spatial Diversity. Pa
Page 103 and 104: fluctuation power at 1 Hz is on the
Page 105 and 106: develops (Pruppacher and Pitter-197
Page 107 and 108: .8 where: f = frequency, in GHz r =
Page 109 and 110: B . k 11.7 26 \ QHz DATA, CTS A VPl
Page 111 and 112: \ for the 11.7 GHz CTS beacon at 50
Page 113 and 114:
● these do not correlate well wit
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. However the XPD dependence on ele
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-. 50 40 30 20 10 0 . T(XPD < ABCIS
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9 electrostatic fields discharge ra
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, f w m I
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. XPD 2 = XPD1 - 20 lo91~ f ~ 1 0.4
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● 3.0 14 0.6 0.3 0,1 0.0s 0.03 0.
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where, for example, for the frequen
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L .- . ., not appear to be sufficie
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D ‘1 may be considered to be rece
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D - 0 m a 80 60 40 20 0 -20 \ — i
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m I s 1 \\ I , t Frequency (GHz) Fi
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-. Table 6.8-1. Cumulative Statisti
Page 139 and 140:
D - The propagation margin is then
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1- * w -180 -190 -m -21 / ---+---4~
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- . . 6.9 UPLINK NOISE IN SATELLITE
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280 260 240 220 200 180 160 140 120
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6.10 REFERENCES Ahmed, I.Y. and L.J
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● International Telecommunication
Page 151 and 152:
Atmospheric Emission observations,
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8.6 and 3.2 mm Radio Waves by Cloud
Page 155 and 156:
I Strickland, J.I. (1974), “Radar
Page 157:
D Wulfsberg, K.N. (1964), “Appare
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