Textbook CHAPTER 8

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Textbook CHAPTER 8
WAVE GUIDES
8.1 INTRODUCTION
8.2 GUIDED MODES IN WAVE GUIDES .
8.3 TM MODES IN RECTANGULAR WAVE GUIDES .
8.4 TE MODES IN RECTANGULAR WAVE GUIDES .
8.5 FIELD CONFIGURATIONS IN WAVE GUIDES .
8.6 EXCITATION OF VARIOUS MODES IN WAVE GUIDES .
8.7 ENERGY FLOW AND ATTENUATION IN WAVE GUIDES .
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TMmn modes in rectangular wave guides
TEmn modes in rectangular wave guides
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It is true in general that modes are orthogonal
to each other
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We can assign an ortho-normal set of modal
functions to every waveguide cross section
Example TE10, TEm0
Mutatis mutandis
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The orthonomral set of modal functions is
complete Every field can be expanded as a
linear combination os modal fields
The coefficients in the expansion are MODAL
VOLTAGES and MODAL CURRENTS
WAVE GUIDE SECTION
TRANSMISSION LINES
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A WAVE GUIDE IS EQUIVALENT TO A SET OF UNCOUPLED
MODES
MODES ARE EXCITED AT THE BOUNDARIES OF THE
WAVE GUIDE SECTION
First, let us look at the excitation of a
semi-infinite wave guide
If we prescribe
, it always can be expanded as
where
are the mode excitations
and e.g.
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Because
Because of orthonormality
Only those modes will be excited which are
present in the feeding field
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Cut-off frequency
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Real ohmic wave resistance
Inductive wave impedance
Capacitive wave impedance
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DISCONTINUITIES IN WAVE GUIDES
Capacitive iris
Equivalent circuit
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Inductive iris
Equivalent circuit
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Cut-off frequency
Coaxial cable
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Homework assignment
Chapter 8
8.4 and 8.5 again, and 8.6
NO NEW PROBLEMS
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