Introduction

This chapter covers the scientific principles that make wireless communication possible. Radio components and the associated frequency range is the primary mode of transmission in the wireless industry.

Radio is the wireless transmission and reception of electric impulses or signals by means of electromagnetic (EM) waves. Electromagnetic waves are present at all frequencies. However, currently we can utilize only a small part of this total spectrum to transmit communication signals. This small subset of frequencies is commonly referred to as the Radio Frequency (RF) spectrum and ranges from about 9 KHz to 300 GHz. Understanding the science behind the communication provides value when you are designing a wireless network, allowing you to understand potential complications such as the signal-to-noise ratio, attenuation and multipath scattering, and channel spacing.

In this chapter we will explore the basic science of EM waves, and how and why radio signals are modulated onto carrier waves; we ll look at antenna design, the relationship between wave propagation technologies and signal power, and what elements make up a wireless network. Finally, a discussion of channels will introduce different cellular schemes and how and why wireless communications are regulated.

Transmitting Radio Signals Over EM Waves

As described in Chapter 1, the German scientist Heinrich Hertz demonstrated in 1887 that electrical energy could be transmitted through space via electromagnetic waves. Even though Professor Hertz was the first to demonstrate this phenomenon, he did not grasp the impact of his discovery. It was a young contemporary of his,...