Since half a century, geostationary satellites have been playing an ever increasing role in global com­munications.The material in this book is intended for students and practical engineers, but should be under­standable by any interested individual with a sound scientific or technical education. It is or­ganized in seven Sections, starting with an overview of the geostationary spacecraft, its archi­tecture, its orbit and its subsystems. Section 2 briefly sketches satellite communications in terms of network structure and outlines the players and their roles in the space business. Section 3 is dedicated to the physical layer of Satcom networks, emphasizing on the definition of coverage areas and frequency plans.Section 4 provides an overview of waveforms, modulation techniques and Forward Error Cor­rection (FEC) encoding, material considered mandatory to understand the principles of satellite link design presented in Section 5, which also includes some details on atmospheric propagation. Section 6 describes the make of a communication payload and provides some guidelines how to design it. Albeit part of the payload, satellite based antennas receive specific attention in Section 7.Practical examples using a hypothetical Satcom system called "ARCTISAT" have been inserted throughout Sections 3 to 7 of the book.