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Unformatted text preview: Slide Presentations for ECE 329, Slide Introduction to Electromagnetic Fields, to supplement “Elements of Engineering to Electromagnetics, Sixth Edition” Electromagnetics,
by Nannapaneni Narayana Rao
Edward C. Jordan Professor of Electrical and Computer Engineering University of Illinois at Urbana-Champaign, Urbana, Illinois, USA Distinguished Amrita Professor of Engineering Amrita Vishwa Vidyapeetham, Coimbatore, Tamil Nadu, India 4.5 Uniform Plane Waves in Dielectrics and Conductors 4.5-3 Special Cases: 1. Perfect dielectric: ( σ = 0 ) γ= jωµ g jωε = jω µε ∴α = 0 no attenuation β = ω µε
jωµ = jωε µ , purely real ε Behavior same as in free space except that ε 0 → ε and µ 0 → µ . 4.5-4 2. Imperfect Dielectric: ( σ ≠ 0 but σ = ωε ) γ=
≈σ 2 jωµ ( σ + jωε ) µ + jω µε ε µ η≈ 1+ j σ ε 2ωε Behavior essentially like in a perfect dielectric except for attenuation. 4.5-5 3. Good Conductor: ( σ ? ωε ) γ= jωµ ( σ + jωε ) ≈ π f µσ ( 1+ j ) ∴α = β ≈ π f µσ
jωµ π fµ η= ≈ ( 1+ j) σ + jωε σ = 2π f µ ∠45o σ Behavior much different from that in a dielectric. 4.5-6 4. Perfect Conductor: ( σ = ∞ ) Idealization of good conductor in the limit that σ → ∞. α → ∞, η → 0
∴ waves can penetrate into a perfect conductor. No No time-varying fields inside a perfect conductor. ...
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This note was uploaded on 01/22/2011 for the course ECE 329 taught by Professor Kim during the Spring '08 term at University of Illinois, Urbana Champaign.
- Spring '08