MATLAB-Based Electromagnetics

1 Electrostatic Field in Free Space 1
1.1 Coulomb's Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Electric Field Intensity Vector Due to Given Charge Distributions . . . . . . . . . 9
1.3 Electric Scalar Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
1.4 Differential Relationship Between the Field and Potential in Electrostatics, Gradient 26
1.5 Electric Dipole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
1.6 Gauss' Law in Integral Form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
1.7 Differential Form of Gauss' Law, Divergence . . . . . . . . . . . . . . . . . . . . . . 31
1.8 Method of Moments for Numerical Analysis of Charged Metallic Bodies . . . . . . 33
2 Electrostatic Field in Dielectrics 41
2.1 Characterization of Dielectric Materials . . . . . . . . . . . . . . . . . . . . . . . . 41
2.2 Dielectric—Dielectric Boundary Conditions . . . . . . . . . . . . . . . . . . . . . . . 46
2.3 Poisson's and Laplace's Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
2.4 Finite-Difference Method for Numerical Solution of Laplace's Equation . . . . . . . 51
2.5 Evaluation of Capacitances of Capacitors and Transmission Lines . . . . . . . . . . 59
2.6 Capacitors with Inhomogeneous Dielectrics . . . . . . . . . . . . . . . . . . . . . . 69
2.7 Dielectric Breakdown in Electrostatic Systems . . . . . . . . . . . . . . . . . . . . . 70
3 Steady Electric Currents 73
3.1 Continuity Equation, Conductivity, and Ohm's Law in Local Form . . . . . . . . . 73
3.2 Boundary Conditions for Steady Currents . . . . . . . . . . . . . . . . . . . . . . . 79
3.3 Relaxation Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.4 Resistance and Ohm's Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
4 Magnetostatic Field in Free Space 86
4.1 Magnetic Force and Magnetic Flux Density Vector . . . . . . . . . . . . . . . . . . 86
4.2 Magnetic Field Computation Using Biot—Savart Law . . . . . . . . . . . . . . . . . 92
4.3 Ampere's Law in Integral Form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
4.4 Differential Form of Ampere's Law, Curl . . . . . . . . . . . . . . . . . . . . . . . . 102
4.5 Magnetic Vector Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
4.6 Magnetic Dipole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
5 Magnetostatic Field in Material Media 106
5.1 Permeability of Magnetic Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
5.2 Boundary Conditions for the Magnetic Field . . . . . . . . . . . . . . . . . . . . . . 108
5.3 Magnetic Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
vi Contents, Preface, and m Files on Instructor Resources
6 Time-Varying Electromagnetic Field 118
6.1 Faraday's Law of Electromagnetic Induction . . . . . . . . . . . . . . . . . . . . . . 118
6.2 Self-Inductance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
6.3 Mutual Inductance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
6.4 Displacement Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
6.5 Maxwell's Equations for the Time-Varying Electromagnetic Field . . . . . . . . . . 130
6.6 Boundary Conditions for the Time-Varying Electromagnetic Field . . . . . . . . . . 132
6.7 Time-Harmonic Electromagnetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
6.8 Complex Representatives of Time-Harmonic Field and Circuit Quantities . . . . . 137
6.9 Instantaneous and Complex Poynting Vector . . . . . .