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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