Special Topics in Electromagnetics

Kun-Mu Chen

• Éditeur: WSPC
• Année: 2013
• ISBN:
  9789814412193
• Sujet: Tecnologia e ingegneria
• Sous-sujet: Radar

A primary resource for graduate teaching and research in advanced electromagnetic materials, Special Topics in Electromagnetics covers some new methods for treating the interaction of electromagnetic field with materials, as well as biological applications and radar identification using electromagnetic waves. This book supplements its content with detailed mathematical derivation and covers some practical applications.

Contents:

• General Maxwell's Equations and Solutions
• Vector Wave Functions and Applications
• Dyadic Green's Functions and Applications
• Biomedical Application of Electromagnetic Waves
• Radar Target Identification with Extinction-Pulse (E-Pulse) Method

Readership: Graduate and research students and working professionals interested in the field of electromagnetics.

Chapter 1

General Maxwell’s Equations and Solutions

Modified Maxwell’s Equations with Magnetic Source Terms

Conventional Maxwell’s equations which express the relations between the field vectors, the electric field

and the magnetic induction

, and the source current density

and charge density ρ are usually written in the following form :

where the displacement vector

and the magnetic field

are defined by

with

as the polarization density,

as the magnetization density, and ε₀ and μ₀ are permittivity and permeability of the free space.

The source current density

and source charge density ρ are related by the equation of continuity:

In a simple medium,

Where ε and μ are the permittivity and permeability of the medium.

The Maxwell’s equations expressed in Eqs. (1.1) to (1.4) are not symmetrical mathematically. Equations (1.1) and (1.2) are different in form and so are Eqs. (1.3) and (1.4) as the result. Why? Because the elementary source for the electric field

is different from that of the magnetic field

. Eq. (1.3) implies that

field starts from or terminates at an electric charge ρ. However, Eq. (1.4) implies that

field does not start from or terminate at a magnetic charge. This is due to the fact that there exists no real magnetic charge (or magnetic monopole). In fact, the smallest unit of the magnetic source is a magnetic dipole which is actually an infinitesimal current loop. The situation is depicted in Fig. 1a. This is the conventional thinking even though there are some reports on the discovery of magnetic monopoles. If these reports are verified in the future, it would not alter the following derivation of t...