An Introduction to 5G

4Spectrum, Antennas and Propagation

This is the first of three chapters that address the underlying technologies that are used by the 5G air interface. One of those technologies is a move to higher radio frequencies in pursuit of a wider bandwidth and a higher data rate. That has several impacts on the coverage of the air interface, which we will review as part of this chapter. We will also introduce some of the phenomena that appear in a multipath propagation environment, which will be useful for later chapters. There are several valuable references for further reading, for example Reference [1], while others are listed in the Bibliography.

4.1 Radio Spectrum

4.1.1 Radio Waves

Electromagnetic waves consist of oscillating electric and magnetic fields, whose frequency f and wavelength λ are related as follows:

(4.1)

where c is the speed of light, approximately 300 000 km s⁻¹. Waves with different frequencies are created and absorbed in different ways, so they are often grouped into a half‐dozen categories that are illustrated in Figure 4.1. Nevertheless, there are no precise boundaries between those categories: instead, they blur into each other.

Figure 4.1 The electromagnetic spectrum.

Radio waves are most easily created by supplying an alternating electric current to ...