Twenty years of international satellite communication

We begin with a brief historical recount of the events leading up to the establishment of INTELSAT and the subsequent growth of that system. We then review the main technical developments that were necessary to establish reliable international satellite communication services. These were spurred, for the most part, by the need to establish a global system and by the quest for increased capacity. While frequencies in several bands have been set aside for fixed satellite communications services (FSS), INTELSAT has primarily used those assigned at 4 and 6 GHz, because initially the technology was the most advanced for these frequencies (and hence, the cost was lower and reliability more assured). Since only 1,100 MHz is allocated for commercial satellite communications at the 4-GHz band used for space-to-earth transmissions, significantly increasing the capacity has entailed using this band several times over. We also discuss additional means by which capacity has been increased, namely, the use of many separate transponders, each covering only a small portion of the available band. Finally, we discuss ways in which FSS satellite systems are likely to evolve