Page 132 - Satellite Communications, Fourth Edition

112 Chapter Four

4.6. Explain what is meant by rain rate and how this is related to specific
attenuation.

4.7. Compare the specific attenuations for vertical and horizontal polarization
at a frequency of 4 GHz and a point rain rate of 8 mm/h which is exceeded for
0.01 percent of the year.

4.8. Repeat Prob. 4.7 for a frequency of 12 GHz.
4.9. Explain what is meant by effective path length in connection with rain
attenuation.

4.10. For a satellite transmission path, the angle of elevation of the earth
station antenna is 35°, and the earth station is situated at mean sea level. The
signal is vertically polarized at a frequency of 18 GHz. The rain height is 1 km,
and a rain rate of 10 mm/h is exceeded for 0.001 percent of the year. Calculate
the rain attenuation under these conditions.

4.11. Repeat Prob. 4.10 when the rain rate of 10 mm/h is exceeded (a) 0.01
percent and (b) 0.1 percent of the year.

4.12. Given that for a satellite transmission El 22°, R 0.01 15 mm/h, h 0
600 m, h R 1500 m, and horizontal polarization is used, calculate the rain
attenuation for a signal frequency of 14 GHz.
4.13. Determine the specific attenuation for a circularly polarized satellite
signal at a frequency of 4 GHz, where a point rain rate of 8 mm/h is exceeded
for 0.01 percent of the year.

4.14. A circularly polarized wave at a frequency of 12 GHz is transmitted from
a satellite. The point rain rate for the region is R 0.01 13 mm/h. Calculate the
specific attenuation.
4.15. Given that for Prob. 4.13 the earth station is situated at altitude 500 m
and the rain height is 2 km, calculate the rain attenuation. The angle of elevation
of the path is 35°.

4.16. Given that for Prob. 4.14 the earth station is situated at altitude 200 m
and the rain height is 2 km, calculate the rain attenuation. The angle of elevation
of the path is 25°.

References
Brussard, G., and D. V. Rogers. 1990. “Propagation Considerations in Satellite Communication
Systems.” Proc. IEEE, Vol. 78, No. 7, July, pp. 1275–1282.
CCIR Report 263-5. 1982. “Ionospheric Effects upon Earth-Space Propagation.” 15th Plenary
Assembly, Vol. VI, Geneva, pp. 124–146.
CCIR Report 564-2. 1982. “Propagation Data Required for Space Telecommunication
System.” 15 Plenary Assembly, Vol. IX, Part 1, Geneva.