Electromagnetic Field Theory Lecture Notes

REFERENCE BOOKS FOR ELECTROMAGNETIC WAVE THEORY AND MICROWAVES.
1) D.CHENG, “ FIELD & WAVE ELECTROMAGNETICS” ADDISON-WESLEY

2) UMRAN S. INAN, AZIZ S. INAN , “ENGINEERING ELECTROMAGNETICS” , ADDISON-WESLEY 1999

3) R.COLLINS, “FOUNDATIONS OF MICROWAVE ENGINEERING” Mc GRAW-HILL 1992

4) D.POZAAR, “MICROWAVE ENGINEERING” ADDISON-WESLEY 1990

FOUR FUNDAMENTAL ELECTROMAGNETIC FUNCTIONS
•

r E r D

r ( r , t ) - Electric Field Intensity

–

(V/m)

•

r (r , t ) - Electric Flux Density (Displacement vector) – (C/m2)

•

r H (rr, t ) - Magnetic Field Intensity

–

(A/m)

•

r r B (r , t ) - Magnetic Flux Density r Jc

–

(Wb/m2)

THREE TYPES OF ELECTRIC CURRENTS
•
r (r , t ) - Conduction Current Density – (A/m2)

r Jc=

•

r r J u (r , t ) - Convection Current Density – (A/m2)

σ = Conductivity (S/m)

r σE

r Ju=

r ρu

r ρ = Free Electric Charge Density – (C/m3), u = Velocity Vector – (m/s) •

r J

d

r (r , t ) - Displacement Current Density – (A/m2)

r r ∂D Jd = ∂t
MAXWELL’S EQUATIONS These four fundamental equations of electromagnetics on the basis of three separate experimentally established facts, namely, Coulomb’s law, Ampere’s law (or the Biot-Savart law), Faraday’s law, and the principle of conservation of electric charge. The validity of Maxwell’s equations is based on their consistency with all of our experimental knowledge to date concerning electromagnetic phenomena. The physical meaning of the equations is better perceived in the context of their integral forms, which are listed below together with their differential counterparts: 1. Faraday’s law is based on the experimental fact that time-changing magnetic flux induces electromotive force:

r r r r E . dl = − ∫ ∂ B . d s ∫C s ∂t r r ∇ × E = − ∂B

∂t

where the contour C is that which encloses the surface S, and where the direction of the line integration over the contour C (i.e., dl) must be consistent with the direction of the