Communications Engineering Desk Reference

Chapter 2.1

Basic features of radio communication systems

Ed da Silva

2.1.1 Introduction

This chapter describes communication systems which use radio waves and signals. Radio signals are useful for two main reasons. They provide a relatively cheap way of communicating over vast distances and they are extremely useful for mobile communications where the use of cables is impractical.

Radio signals are generally considered to be electromagnetic signals which are broadcast or radiated through space. They vary in frequency from several kilohertz¹ to well over 100 GHz (10¹¹ Hz). They include some well known public broadcasting bands: long-wave (155–280 kHz), medium-wave (522–1622 kHz), short-wave (3–30 MHz), very high frequency (VHF) FM band (88–108 ...