The RF Link

This chapter first introduces the fundamental elements of the communications satellite Radio Frequency (RF) or free space link. It then introduces basic transmission parameters, such as antenna gain, beamwidth, free‐space path loss, and the basic link power equation. In this chapter, the authors develop procedures to determine the equivalent noise temperature for specific elements of interest in the communications circuit. The chapter discusses three types of devices, including active devices, passive devices, and the receiver antenna system. The chapter deals with a description of a) parameters of interest describing the desired signal power levels on the satellite communications RF link, and, b) parameters of interest describing the noise power levels on the link. It brings together these concepts to define overall RF link performance in the presence of system noise. These results will be essential for defining satellite system design and link performance for a wide range of applications and implementations.