Propagation Effects on Satellite Communication

This course consist of introduction to atmospheric absorption, cloud attenuation, tropospheric and ionospeheric scintillation and low angle fading, rain induced attenuation, rain induced cross polarization interference. As we know that, a signal traveling between an earth station and a satellite must pass through the earth’s atmosphere, including the ionosphere. The signal energy is absorbed in earth’s atmosphere due to presence of atmospheric gases. These loss is called as atmospheric absorption. There are various losses occurs at signal transition from earth station to satellite. These losses are varying as per the weather condition. Therefor the losses occurs due to weather related losses are referred as atmospheric losses.

Another term losses due to ionosphere losses. When the radio waves traveling between satellites and earth stations must pass through the ionosphere. The ionosphere is the upper region of the earth’s atmosphere, which has been ionized, mainly by solar radiation, in day it has different height from surface of earth and in night it changes due to no solar radiation. . In ionosphere the free electrons are not uniformly distributed but form in layers. The signal passes through the ionosphere gives rise to fluctuations in signal that effects include scintillation, absorption, variation in the direction of arrival, propagation delay, dispersion, frequency change, and polarization rotation. All these effects can be minimized by increasing the signal frequency.