P1246990939kMOAU

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EE 30358 - Electromagnetic Fields and Waves II
IN NATURE
PLANE WAVE PROPAGATION, REFLECTION,
REFRACTION LINEAR, CIRCULAR, ELLIPTIC
POLARIZATION PROPGATION IN CONDUCTIVE MEDIUM
GUIDED EM WAVES
ENERGY PROPGATES IN THE DIELECTRIC, NOT IN
WIRES TRANSMISSION LINES, WAVEGUIDES,
DISCONTINUITIES
RADIATION ANTENNAS
ACCELERATED CHARGE RADIATES, RETARDED
POTENTIALS HERTZ-DIPOLE, LINEAR WIRE ANTENNAS,
ARRAYS
CIRCUIT REPRESENTATION OF EM FIELDS AND WAVES
MAXWELLS EQUS.
KIRCHHOFFS EQUS.
IMPEDANCE ADMITTANCE SCATTERING
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HELPFUL EQUATIONS FOR PLANE WAVES


Region1 Region 2 Region
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Pw1 MIDTERM 1
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HELPFUL EQUATIONS FOR REFLECTION AND REFRACTION


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Rw1
Rw2
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HELPFUL EQUATIONS FOR GUIDED WAVES


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is connected to a
Gw1 An antenna of input impedance of
transmitter through a 5 m long coaxial cable of
dimensions
. The input voltage of the transmitter is
and its internal impedance is
Determine the following a) The input impedance
of the cable
when terminated by the antenna
b) The average power delivered to the load
antenna.
characteristic impedance is terminated
Gw2. A transmission line of
by a load impedance
Design an impedance matching two-port for
and determine the power delivered to the load at
frequencies
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Gw3. An air filled rectangular waveguide of
dimensions operates in the
frequency band
Determine all the propagating modes in
the frequency band, if
and
Gw4. An air filled waveguide has the inside
dimensions of
and it is operating in the TE10 mode.
We measure the VSWR using a slotted wave guide.
The distance between two successive minima was
0.1 m. Determine the operating frequency!
The amplitude of the electric field is 1000 V/m.
Calculate the total power Transmitted down the
wave guide!
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HELPFUL EQUATIONS FOR RADIATION ANTENNAS


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Ant1 Determine the radiation resistance and the
directivity of a Hertz-dipole (short
linear antenna) of length
Determine the radiation resistance and the
directivity of a linear antenna of length
Ant 2
How does the radiation resistance change it the
length is fixed but the frequency changes from
0.5 to 1.5 GHz?
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HELPFUL EQUATIONS FOR CIRCUIT REPRESENTATION OF
EM FIELDS AND WAVES
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GUIDED ELECTROMAGNETIC WAVES
TRANSMISSION LINES
WAVEGUIDES
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ANALOGY BETWEEN A NORMALLY INCIDENT, LINEARLY
POLARIZED PLANE WAVE AND WAVE ALONG A
TRANSMISSION LINE
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VOLTAGE STANDING-WAVE RATION (VSWR) ALONG
LOSSLESS TRANSMISSION LINES
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Single-wire wave guides
Two-wire wave guides
Only TE TM modes
TEM TE TM modes
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TMmn modes in rectangular wave guides
TEmn modes in rectangular wave guides
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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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Cut-off frequencies
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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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DISCONTINUITIES IN WAVE GUIDES
Capacitive iris
Equivalent circuit
Inductive iris
Equivalent circuit
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RADIATION - ANTENNAS
ACCELERATED CHARGE RADIATES, RETARDED
POTENTIALS HERTZ-DIPOLE, LINEAR WIRE ANTENNAS,
ARRAYS
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RETARDED POTENTIALS
Current
Vector potential
For static case solution is known
For dynamic case the solution is the retarded
potential
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RADIATION RESISTANCE
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HELPFUL EQUATIONS FOR RADIATION ANTENNAS


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CIRCUIT REPRESENTATION OF EM FIELDS AND WAVES
MAXWELLS EQUS.
KIRCHHOFFS EQUS.
IMPEDANCE ADMITTANCE SCATTERING
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CIRCUIT MODELS OF EM FIELDS AND WAVES
MAXWELLS EQUATIONS ? KIRCHOFFS EQUATIONS
KIRCHHOFF I. CONSERVATION OF CHARGE
KIRCHHOFF II. CONSERVATION OF ENERGY
GENERATORS CHARGE SEPARATORS
Thevenin Norton-Meier Equivalents
LINEAR-PASSIVE ONE-PORTS (finite volume, no
radiation)
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IMPEDANCE MATRIX
3. Linear TWO-PORT
ADMITTANCE MATRIX
RECIPROCITY
and non-negative
PASSIVE ONE-PORT
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If two modes are propagating
Two transmission line PORTS (Two-Port)
If more waveguides form a junction
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IMPEDANCE MATCHING
QUARTER-WAVELENGTH TRANSFORMER
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IMPEDANCE MATCHING WITH A QUARTER-WAVELENGTH
TRANSFORMER
Transmission line feeding the load
Example
Dipole antenna at
Quarter wavelength matching
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ONE-PORTS
TWO-PORTS
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TWO-PORTS
ONE-PORTS
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Linear, passive. reciprocal two-ports
Lossless one-port
Lossless two-ports
IS UNITARY
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