section of transmission line that is less than a quarter wavelength can take
the place of an inductor, at the ultra-high frequencies.
An actual coil
having a specific amount of inductance would be too small to be practical at
such high frequencies.
Figure 23.
Properties of Transmission Lines One-Half
Wavelength or Less.
Learning Event 2:
ARTIFICIAL TRANSMISSION LINES
1.
General.
a. A transmission line is used to guide RF energy from one place to
another with a minimum loss of energy.
In addition, sections of RF
transmission lines are used as coils and capacitors. For example, an open
circuited quarter-wave line acts as a coil and capacitor in series.
An
open-circuited, half-wave line acts as a coil and capacitor connected in
parallel.
b. Since a transmission line acts like a combination of coils and
capacitors, it follows that we can connect coils and capacitors in
arrangements that will act like transmission lines.
We call this circuit
arrangement of coils and capacitors artificial transmission lines (ATL).
c. Two major ATL uses we will discuss in this text are:
(1) As pulse-forming networks (PFN), to form pulses used in radar.
(2) As delay lines to delay pulses.
2.
Comparing real and artificial transmission lines.
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