Lect28AntennaBasics

Lect28AntennaBasics - ECE 3030 Electromagnetic Fields and...

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1 ECE 3030 Electromagnetic Fields and Waves Fall 2009 Lecture 28 2009/11/2 Antenna Basics Radiation by Oscillating Charges and Currents Retarded lt t l l h l l d ) Potentials 1 Swartz 08/11/4 Electromagnetic Fields and Waves – Fall 2009 Lecture 28: Instructor: Dr. Wesley E. Swartz Retarded ( slow, not mentally challenged 91 x z q ( t ) -q ( t ) Problem Assignments Demo 10 Problems (Tuesday, November 3) : Problem 13.40: Transients on shorted transmission line. Problem 15.16: Propagation modes of a dielectric slab waveguide. Problem 16.7: Finding propagating modes of a rectangular waveguide. Just a few; rest for homework. Workshop 10 Problems (Thursday, November 5) : Problem 13.34: Transient caused by shorting source. Problem 15 20: Ai Sili di l t i l b id 2 Swartz 08/11/4 Electromagnetic Fields and Waves – Fall 2009 Lecture 28: Problem 15.20: Air-Silicon dielectric slab waveguide. Problem 16.22: Waveguide Smith Chart problem. Homework 10 Problems (due Tuesday, November 10) : Problem 15.19: Conductor-Silicon dielectric slide waveguide. Problem 16.7: Finding propagating modes of a rectangular waveguide. The rest of those not given in demo (10 total). Problem 13.33: Transient caused by shorting load. Where Are We? We started with static fields. We then moved to dynamic (time dependent) fields: Electro-magnetic TEM plane waves. In free space. In dielectrics (isotropic and non-isotropic). In conductors. Guided electro-magnetic waves By transmission lines (TEM waves) 3 Swartz 08/11/4 Electromagnetic Fields and Waves – Fall 2009 Lecture 28: By transmission lines (TEM waves). By dielectric slab waveguides (TE or TM waves). By metal plate waveguides (TE or TM waves). By rectangular metal waveguides (TE or TM waves). Now how do we couple waves in transmission lines to waves in free space? Antennas create the sources of our waves. Antennas receive signals carried by E & M waves Maxwell’s Equations and Radiation Time-varying currents are the “source” or “driving” terms for the wave equation: () 0 , . = t r H o μ t t r H t r E o = × , , () () t r t r E o , , . ρ ε = t t r E t r J t r H o + = × , , , t t r E c t t r J t t r H t r E o o = × = × × , 1 , , , 2 2 2 4 Swartz 08/11/4 Electromagnetic Fields and Waves – Fall 2009 Lecture 28: t t r J t t r E c t r E o = + × × , , 1 , 2 2 2 0 , , . = + t t r t r J 911 Maxwell’s equations predict outgoing radiation from sinusoidally time-varying currents (and charges). Recall that current and charge densities are related through the continuity equation: A Review of Electro- and Magneto- quasistatics and Potentials t r t r E o , , .
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This note was uploaded on 11/26/2009 for the course ECE 3030 at Cornell.

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Lect28AntennaBasics - ECE 3030 Electromagnetic Fields and...

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