RF and Microwave Engineering: Fundamentals of Wireless Communications

Chapter 8

Radio Wave Propagation

Spherical electromagnetic waves that emanate from a transmitting antenna experience a reduction in field strength as the distance to the antenna increases. Furthermore, in terrestrial wireless communication links, EM waves interact with obstacles (buildings, walls, trees, hills, etc.) leading to absorption, diffraction and scattering of waves. Consequently, the field strength decreases even more quickly than in free space. In order to design and operate wireless communication systems it is essential to estimate the path loss from transmitter to receiver. For a given transmit power the path loss determines the received power and hence the coverage of the wireless system.

In this chapter we start by illustrating physical aspects of electromagnetic wave propagation. Furthermore, fundamental mathematical models that predict path loss in simple environments are derived from basic theory. Finally, we present more complex models to predict path loss in real environments.