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MAXWELL’S EQUATIONS AND TRANSMISSION MEDIA CHARACTERISTICS
ENEE 482 Spring 2002 DR. KAWTHAR ZAKI
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MICROWAVE CIRCUIT ELEMENTS AND ANALYSIS
Two conductor wire Coaxial line Shielded Strip line Dielectric ENEE482
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Common Hollow-pipe waveguides
Rectangular guide Ridge guide Circular guide ENEE482
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STRIP LINE CONFIGURATIONS
W SINGLE STRIP LINE COUPLED LINES COUPLED STRIPS TOP & BOTTOM COUPLED ROUND BARS ENEE482
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MICROSTRIP LINE CONFIGURATIONS
SINGLE MICROSTRIP TWO COUPLED MICROSTRIPS TWO SUSPENDED SUBSTRATE LINES SUSPENDED SUBSTRATE LINE ENEE482
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TRANSVERSE ELECTROMAGNETIC (TEM): COAXIAL LINES
TRANSMISSION MEDIA TRANSVERSE ELECTROMAGNETIC (TEM): COAXIAL LINES MICROSTRIP LINES (Quasi TEM) STRIP LINES AND SUSPENDED SUBSTRATE METALLIC WAVEGUIDES: RECTANGULAR WAVEGUIDES CIRCULAR WAVEGUIDES DIELECTRIC LOADED WAVEGUIDES ANALYSIS OF WAVE PROPAGATION ON THESE TRANSMISSION MEDIA THROUGH MAXWELL’S EQUATIONS ENEE482
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Electromagnetic Theory Maxwell’s Equations
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Auxiliary Relations: ENEE482
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Maxwell’s Equations in Large Scale Form
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Maxwell’s Equations for the Time - Harmonic Case
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Boundary Conditions at a General Material Interface
h E1t E2t m1,e1 m2,e2 D1n D2n h Ds ENEE482
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Fields at a Dielectric Interface
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+ + + n rs Js Ht ENEE482
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The magnetic wall boundary condition
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Wave Equation ENEE482
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Plane Waves ENEE482
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H is perpendicular to E and to n. (TEM waves)
z y E n H x H is perpendicular to E and to n. (TEM waves) ENEE482
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Plane Wave in a Good Conductor
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Boundary Conditions at the Surface of a Good Conductor
The field amplitude decays exponentially from its surface According to e-u/ds where u is the normal distance into the Conductor, ds is the skin depth ENEE482
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Reflection From A Dielectric Interface
Parallel Polarization e x Er n2 e0 Et n3 q2 q3 q1 z n1 Ei ENEE482
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Energy and Power Under steady-state sinusoidal time-varying
Conditions, the time-average energy stored in the Electric field is ENEE482
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Poynting Theorem ENEE482
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Circuit Analogy L R I V C ENEE482
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Potential Theory ENEE482
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Solution For Vector Potential
J (x’,y’, z’) R (x,y,z) r’ r ENEE482
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Waves on An Ideal Transmission Line
Rg z Lumped element circuit model for a transmission line Ldz I(z,t)+dI/dz dz I(z,t) V(z,t) Cdz V(z,t)+dv/dz dz ENEE482
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Steady State Sinusoidal Waves
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Transmission Line Parameters
C2 C1 S ENEE482
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Terminated Transmission Line
ZL Zc Z To generator ENEE482
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Transmission Lines & Waveguides
Wave Propagation in the Positive z-Direction is Represented By:e-jbz ENEE482
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Modes Classification: 1. Transverse Electromagnetic (TEM) Waves
2. Transverse Electric (TE), or H Modes 3. Transverse Magnetic (TM), or E Modes 4. Hybrid Modes ENEE482
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TEM WAVES ENEE482
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TE WAVES ENEE482
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TM WAVES ENEE482
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TEM TRANSMISSION LINES
Coaxial Two-wire Parallel -plate a b e ENEE482
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COAXIAL LINES a b e ENEE482
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THE CHARACTERISTIC IMPEDANCE OF A COAXIAL IS Z0
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Zc OF COAXIAL LINE AS A FUNCTION OF b/a
1 10 100 20 40 60 80 120 140 160 180 200 220 240 260 = er Zo ENEE482
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Transmission line with small losses
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Qc OF COAXIAL LINE AS A FUNCTION OF Zo
er Zc ENEE482
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Parallel Plate Waveguide
TEM Modes y d x w ENEE482
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TM modes ENEE482
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TE Modes ENEE482
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COUPLED LINES EVEN & ODD
MODES OF EXCITATIONS AXIS OF EVEN SYMMETRY AXIS OF ODD SYMMETRY P.M.C. P.E.C. ODD MODE ELECTRIC FIELD DISTRIBUTION EVEN MODE ELECTRIC FIELD DISTRUBUTION =ODD MODE CHAR. IMPEDANCE =EVEN MODE CHAR. IMPEDANCE Equal currents are flowing in the two lines Equal &opposite currents are flowing in the two lines ENEE482
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WAVEGUIDES HOLLOW CONDUCTORS RECTANGULAR OR CIRCULAR.
PROPAGATE ELECTROMAGNETIC ENERGY ABOVE A CERTAIN FREQUENCY (CUT OFF) INFINITE NUMBER OF MODES CAN PROPAGATE, EITHER TE OR TM MODES WHEN OPERATING IN A SINGLE MODE, WAVEGUIDE CAN BE DESCRIBED AS A TRANSMISSION LINE WITH C/C IMPEDANCE Zc & PROPAGATION CONSTANT g ENEE482
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WAVEGUIDE PROPERTIES FOR A W/G FILLED WITH DIELECTRIC er : ENEE482
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PROPAGATION PHASE CONSTANT:
FOR RECTANGULAR GUIDE a X b, CUTOFF WAVELENGTH OF TE10 MODES ARE: : CUT OFF FREQUENCY IN GHz (lc INCHES): FOR CIRCULAR WAVEGUIDE OF DIAMETER D CUTOFF WAVE LENGTH OF TE11 MODE IS: lc = D DOMINANT MODES ARE TE10 AND TE11 MODE FOR RECTANGULAR & CIRCULAR WAVEGUIDES ENEE482
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RECTANGULAR WAVEGUIDE
MODE FIELDS y b z x a CONFIGURATION ENEE482
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TE modes ENEE482
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TEmn MODES ENEE482
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The dominant mode is TE10 ENEE482
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TMmn MODES ENEE482
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TE Modes of a Partially Loaded Waveguide
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CIRCULAR WAVEGUIDE MODES
y r a f x z ENEE482
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TE Modes ENEE482
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TEnm MODES ENEE482
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TMnmMODES ENEE482
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Cutoff frequencies of the first few TE
And TM modes in circular waveguide TE11 TE21 TE01 TE31 1 fc/fcTE11 TM01 TM11 TM21 ENEE482
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ATTENUATION IN WAVEGUIDES
ATTENUATION OF THE DOMINANT MODES (TEm0) IN A COPPER RECTANGULAR WAVEGUIDE DIM. a X b, AND (TE11) CIRCULAR WAVEGUIDE, DIA. D ARE: WHERE f IS THE FREQUENCY IN GHz ENEE482
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ATTENUATION IN COPPER WAVEGUIDES
DUE TO CONDUCTOR LOSS ENEE482
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Higher Order Modes in Coaxial Line
TE Modes: ENEE482
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Grounded Dielectric Slab
x z Dielectric Ground plane TM Modes ENEE482
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Stripline y w b x z Approximate Electrostatic Solution: y b/2 a/2 -a/2
a/2 -a/2 ENEE482
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Microstrip y w d -a/2 x a/2 ENEE482
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The Transverse Resonance Technique
TM Modes for the parallel plate waveguide y y d d w x ENEE482
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MODES IN DIELTECTRIC LOADED WAVEGUIDE
b er1 a er2 CATEGORIES OF FIELD SOLUTIONS: TE0m MODES TM0m MODES HYBRID HEnm MODES ENEE482
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BOUNDARY CONDITIONS FIELDS SATISFY THE WAVE EQUATION,
SUBJECT TO THE BOUNDARY CONDITIONS Ez , Ef , Hz , Hf ARE CONTINUOUS AT r=b Ez , Ef VANISH AT r=a ENEE482
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WHERE A IS AN ARBITRARY CONSTANT
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Characteristic equation
Where z=x1a is the radial wave number in er ENEE482
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For n = 0, the Characteristic Equation Degenerates in two
Separate Independent Equations for TE and TM Modes: For TE Modes And: For TM Modes ENEE482
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COMPLEX MODES COMPLEX PROPAGATION CONSTANT : g = a +jb
ONLY HE MODE CAN SUPPORT COMPLEX WAVES PROPAGATION CONSTANT OF COMPLEX MODES ARE CONJUGATE : COMPLEX MODES DON’T CARRY REAL POWER COMPLEX MODES CONSTITUTE PART OF THE COMPLETE SET OF ELECTROMAGNETIC FIELD SPACE COMPLEX MODES HAVE TO BE INCLUDED IN THE FIELD EXPANSIONS FOR CONVERGENCE TO CORRECT SOLUTIONS IN MODE MATCHING TECHNIQUES. ENEE482
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OPTICAL FIBER 2a e1 IN CIRCULAR CYLINDRICAL COORDINATES:
Step-index fiber ENEE482
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For the symmetric case n=0, the solution break into Separate
TE and TM sets. The continuity condition for Ez1= Ez2 and Hf1= Hf2 at r=a gives for the TM set: The continuity condition for Hz1= Hz2 and Ef1= Ef2 at r=a gives for the TE set: If n is different from 0, the fields do not separate into TM and TE types, but all the fields become coupled through continuity conditions. ENEE482
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Parallel Plate Transmission Line
b c er Partially loaded parallel Plate waveguide y x ENEE482
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Low Frequency Solution
When the frequency is low, ENEE482
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y c b er a x -W W ENEE482
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High Frequency Solution:
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Microstrip Transmission Line
w y H x ENEE482
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Boundary conditions: ENEE482
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