Propagation Effects Handbook for Satellite Systems - DESCANSO ...

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where Tm is the ambient temperature, Y is the absorption coefficient, and 7 is the optical depth to the point under consideration. In radio engineering terms ‘ 7 = 4.343 A dB (6.8-4) where A is the absorption over the path in question, in dB. For frequencies above 10 GHz, the second term on the righthand side of Eq. (6.8-3) reduces to 2.7 K, the cosmic background component, unless the Sun is in the antenna beam, as illustrated in Figure 6.8-1. For an isothermal atmosphere (Tm constant with height), substituting Ydl = dT in Eq. (6.8-3) yields T~=Tm(l-e’)=Tm [ 1-10-* 1 K (6.8-5) where A is again atmospheric absorption in dB. The value of T m taken in Eq. (6.8-4) ranges from 260 to 280 K. One relationship used to determine a value of T m from surface measured temperature is (Wulfsberg-1964) T m = 1.12 Ts - 50 K (6.8-6) where Ts is the surface temperature in K. Noise temperature (or brightness temperature) curves for 3, 7.5, and 17 g/m3 surface water vapor content, with the US Standard Atmosphere for the two lower values and the Tropical Atmosphere for the highest value, have been published by Smith (1982) and reproduced in CCIR Report 720-2 (CCIR-1986h). Examples for an average humidity state (7.5 g/m 3 at the surface) are reproduced as Figures 6-8-2 and 6.8-3. 6-132 -
D - 0 m a 80 60 40 20 0 -20 \ — i \ NTUM VI OOSMIC’ 100 1 GHz 10 100 1 THz FREQUENCY 2,9x10 8 2.9x10 5 290. Figure 6.8-1. Noise Factor and Brightness Temperature from Natural Sources observed on Satellite Downlinks [Source: Spaulding and Hagn - 1978] 0.29
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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
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Frequency (GHz) 10 15 20 30 40 80 1
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If PW is not available from local w
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. . The equivalent heights for oxyg
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m t TEMPERATURE rC) o 5 10 15 20 25
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6.3 PREDICTION OF CUMULATIVE STATIS
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LSTATION LOCATION AND ELEVATION STE
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The models require the following in
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I z za E 100 g w ~ z z K 50 a) ALL
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B . . . t- I I I I I 1 11/1 - . . .
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.- . 9 s@EQ - If Z S D, compute the
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1 0.02 0.05 0.2 0.5 4. Compute D: U
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I . ,. . ~ q 8 H v ~ 1.0 0.8 0.6 0.
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Step 6 Calculate the attenuation ex
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m I : STEP 1 SELECT CLIMATE ZONE FR
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9 10.OOOO 1.0000 0,1ooo 0.0100 0.00
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1 6.3.3 Estimates of Attenuation Gi
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● We now proceed exactly as in th
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STEP 1 GIVEN: STATION PARAMETERS SA
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. B . . . 4. Repeat the process for
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. . ● 100 10 1.0 .1 .01 . . RAIN
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not normally available~ but empiric
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● The intensity-duration-frequenc
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- GIVEN: STATION PARAMETERS OPERATI
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m I s 70 2(J I 10 0 a) BY SEASONS
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.“ ● change in rain rater the r
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m To x o 6 x(n wux!- (5 zawwvxw x 1
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● ✎ ✎ ✎ 10 1 0.1 0.01 0 . -
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● ✎ ✎ ✎ appears to be gener
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6.4.2.3 Statistics of Microwave Eff
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● For each hour’s observations,
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Plots of noise temperature and atte
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.- I where Lf is the fog extent~ in
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than a minute and on spatial scales
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. . . 022 = angle-of-arrival varian
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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
Page 115 and 116: . However the XPD dependence on ele
Page 117 and 118: -. 50 40 30 20 10 0 . T(XPD < ABCIS
Page 119 and 120: 9 electrostatic fields discharge ra
Page 121 and 122: , f w m I
Page 123 and 124: . XPD 2 = XPD1 - 20 lo91~ f ~ 1 0.4
Page 125 and 126: ● 3.0 14 0.6 0.3 0,1 0.0s 0.03 0.
Page 127 and 128: where, for example, for the frequen
Page 129 and 130: L .- . ., not appear to be sufficie
Page 131: D ‘1 may be considered to be rece
Page 135 and 136: m I s 1 \\ I , t Frequency (GHz) Fi
Page 137 and 138: -. Table 6.8-1. Cumulative Statisti
Page 139 and 140: D - The propagation margin is then
Page 141 and 142: 1- * w -180 -190 -m -21 / ---+---4~
Page 143 and 144: - . . 6.9 UPLINK NOISE IN SATELLITE
Page 145 and 146: 280 260 240 220 200 180 160 140 120
Page 147 and 148: 6.10 REFERENCES Ahmed, I.Y. and L.J
Page 149 and 150: ● International Telecommunication
Page 151 and 152: Atmospheric Emission observations,
Page 153 and 154: 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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