What are the advantages and disadvantages of the communication system using space wave in atmosphere?

Explanation

Advantages of communication through space wave is that, absorption of these waves of high or very high frequencies in atmosphere is negligible. Hence, if there is no other problem, a long distance communication can be possible using space wave. On the other hand, space wave propagates in a straight line. Whatever be the height of the transmiting and receiving antenna, due to the curvature fo earth surface, the wave cannot advance beyond a certain limit (this distance is called redio horizon.)
To remove the limitation of radio horizon, a number of antennas are installed one after another so that each antenna receives the transmitted message and immediately retransmits it to the next one. In this way. radio horizon can be enlarged by a great extent.For long distance communication, instead of installing series of antennas, space wave is transmitted to an artificial satellite, placed at a very high altitude from earth surface. the wave is then reflected by the satellite to the distant places of earth.