Chapter 2 of Pozar Microwave Engineering Slide

1. TRANSMISSION LINE (TL)
THEORY

2. WEEK 1
• CLASS 1:The lumped-element circuit model for a
transmission line,Wave propagation in a
transmission line
• CLASS 2: Field analysis of transmission lines,
Classification of transmission lines,

3. WEEK 2
• CLASS 3:The terminated lossless transmission line,
VSWR,The Smith Chart.
• CLASS 4:The quarter wave transformer,Transients
on transmission lines, Generator and load
mismatches

4. MICROWAVETRANSMISSION LINES

5. A transmission line is a system that is capable of “guiding” the
energy transfer between a generator and a load
Derivation of the Telegrapher’s Eqtn
Equation (6) - Board
}
Gives rise to voltage
and current that is a
function of time and
distance
Lumped element
circuit model of
a TL

6. WAVE PROPAGATION
IN ATRANSMISSION LINE
Wave Propagation in TL Equation:
Equation (7) - Board

7. TYPES OFTRANSMISSION LINES
Microstrip Line Waveguide Coax Cable
Field Lines

8. SEVERAL “CONCERNS”WITHTL
CHARACTERISTIC
IMPEDANCE
CUT-OFF
FREQUENCY
ELECTROMAGNETIC
MODE
Ratio of the voltage
to current when
there is no reflection
from the load
(infinitely long line)
Frequency at which
the desirable field
patterns are excited
in any type ofTL.
The EM field pattern
measured at a plane
perpendicular (i.e.,
transverse) to the
propagation direction
of the wave. Note that
aTL can have more
than one mode

9. TYPE OF EM MODE
Transverse
Electric-Magnetic (TEM)
Transverse Electric
(TE)
Transverse Magnetic
(TM)
Neither electric nor
magnetic field in the
direction of propagation
No electric field in the
direction of propagation.
These are sometimes
called H modes because
there is only a magnetic
field along the direction
of propagation
No magnetic field in the
direction of propagation.
These are sometimes
called E modes because
there is only an electric
field along the direction of
propagation

10. MICROSTRIP LINE
Dielectric
CHARACTERISTIC IMPEDANCE
CUT-OFF FREQUENCY
ELECTROMAGNETIC
MODE
SIDEVIEW
Fundamental Mode:
Quasi TEM
@ ‘d’
Anything above the fc, a different EM mode is excited (higher-
order mode)

11. RECTANGULAR WAVEGUIDE
Dielectric
CHARACTERISTIC IMPEDANCE
CUT-OFF FREQUENCY
ELECTROMAGNETIC MODE
Fundamental Mode:
TE(10)
@ ‘d’
Anything above the fc, a different EM mode is excited (higher-
order mode)
TE TM