Preface

In this book, a variety of topics related to electromagnetic fields and waves are extensively discussed. The topics encompass the physics of electromagnetic waves, their interactions with different kinds of media, and their applications and effects.

 Chapter 1 gives an overview of the basic framework of electromagnetism. The topics covered in this chapter include a succinct illustration of electric and magnetic fields as a result of charges at rest and in motion, the range of frequencies of electromagnetic radiation, as well as the mathematical laws that govern electromagnetics.

Chapters 2 and 3 are related to the sources of electromagnetic waves. In Chapter 2, the generation of electromagnetic waves—microwaves, in particular—in traveling wave tubes based on Cherenkov's radiation mechanism is extensively discussed. Since many modern microwave and millimeter-wave systems, used in communications and plasma physics, require high input power, the authors of Chapter 3 describe the designs of different power combiners to amplify the magnitude of the electromagnetic signals.

Chapters 4 to 8 analyze the behavior and interactions of electromagnetic fields and waves in different types of media, i.e., in general dielectric media (Chapter 4), a rotating dielectric medium (Chapter 5), magnetic materials (Chapter 6) and metamaterials (Chapters 7 and 8).

 The final chapter (Chapter 9) presents an analysis on the effects of electromagnetic radiation on living things. The authors have used chick embryos in their in vivo studies.

I would like to take this opportunity to thank Ms. Sandra Maljavac, Author Service Manager, IntechOpen.

> **Kim Ho Yeap**  Associate Professor, Department of Electronic Engineering, Faculty of Engineering and Green Technology, Universiti Tunku Abdul Rahman, Malaysia
