Satellite Communications Payload and System

Chapter 3

Antenna

3.1 Introduction

This chapter is on the payload unit which is the most eye-catching—the antenna. Along with the solar panels, the antennas make a satellite look like a satellite. Antennas easily excite enthusiasm in some people: most antennas are big, many of them move, and antenna deployment videos are exciting, but what is more fun is to watch an antenna engineer demonstrate a two-axis deployment with his arm.

This chapter applies, as does the rest of the book, to communications satellites on orbit today or about to be launched. Also included are antennas developed by satellite manufacturers, because if a satellite manufacturer has spent the time and money to develop an engineering model, the probability is high that the manufacturer flies it within a few short years of reporting on it.

By far most payload antennas are for communications links between satellite and ground, but a few are for satellite-to-satellite crosslinks, of which we will mention three in the course of the chapter.

Excellent line drawings of all communication satellites up to 2007, which clearly show the antennas, can be found in Martin et al. (2007), along with brief but comprehensive descriptions of the spacecraft.

Here is a brief explanation of antennas as background for the detailed description that the rest of the chapter provides. A reflector is commonly called a “dish.” A reflector antenna may have one or two reflectors. If it has two, the larger one is the main reflector and the ...