Page 155 - Satellite Communications, Fourth Edition

Polarization 135

received at an earth station which is west of the satellite and in the northern
hemisphere. Will the wave received at the earth station be vertically polarized?
Give reasons for your answer.

5.16. Explain what is meant by horizontal polarization of a satellite signal. A
horizontally polarized wave is transmitted from a geostationary satellite and
is received at an earth station which is west of the satellite and in the northern
hemisphere. Will the wave received at the earth station be horizontally
polarized? Give reasons for your answer.

5.17. A geostationary satellite stationed at 90°W transmits a vertically
polarized wave. Determine the polarization of the resulting signal received at
an earth station situated at 70°W, 45°N.

5.18. A geostationary satellite stationed at 10°E transmits a vertically polarized
wave. Determine the polarization of the resulting signal received at an earth
station situated at 5°E, 45°N.

5.19. Explain what is meant by cross-polarization discrimination and briefly
describe the factors which militate against good cross-polarization discrimination.
5.20. Explain the difference between cross-polarization discrimination and
polarization isolation.

5.21. A linearly polarized wave traveling through the ionosphere suffers a
Faraday rotation of 9°. Calculate (a) the polarization loss and (b) the cross-
polarization discrimination.
5.22. Why is Faraday rotation of no concern with circularly polarized waves?

5.23. Explain how depolarization is caused by rain.

5.24. A transmission path between an earth station and a satellite has an
angle of elevation of 32° with reference to the earth. The transmission is
circularly polarized at a frequency of 12 GHz. Given that rain attenuation on
the path is 1 dB, calculate the cross-polarization discrimination.

5.25. Repeat Prob. 5.24 for a linearly polarized signal where the electric field
vector is parallel to the earth at the earth station.

5.26. Repeat Prob. 5.24 for a linearly polarized signal where the electric field
vector lies in the plane containing the direction of propagation and the local
vertical at the earth station.

5.27. Repeat Prob. 5.24 for a signal frequency of 18 GHz and an attenuation
of 1.5 dB.