a. Figure 24 shows how ATLs compare to real transmission lines.
Transmission lines are similar to ordinary circuits in that they have
inductance, capacitance, and resistance.
b. Part A of Figure 24 shows a real transmission line and its
equivalent circuit. The properties of a transmission line are distributed
throughout the line and can be considered as a number of coils connected in
series and capacitors shunted across the line.
The coils have a small
amount of resistance and the capacitors have some conductance. To make an
ATL, all you need are coils and capacitors that have the same lumped
inductance and capacitance value as in a real line.
Part B of Figure 24
shows how coils and capacitors can be connected in "pi," "L," or "T"
sections. Any number of sections may be used to make an ATL. Both the real
and artificial lines oppose current flow.
Figure 24.
Comparison of Real and Artificial
3.
Characteristic impedance and characteristic resistance.
a. A real transmission
line presents a characteristic impedance
(symbolized by Zo) to the flow
of RF energy. This characteristic impedance
of a real line is equal to the
square root of the inductance divided by the
capacitance. This is expressed
as the formula:
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