transmission line. Thus, the behavior of a finite line may be quite different

from that of the infinite line.

3-90. The equivalent circuit of an open-ended transmission line is shown in

figure 3-24, view A. Again, losses are to be considered as negligible, and L is

lumped in one branch. Assume that (1) the battery in this circuit has an

internal impedance equal to the characteristic impedance of the transmission

line (Zi = Z0); (2) the capacitors in the line are not charged before the battery

is connected; and (3) because the line is open-ended, the terminating

impedance is infinitely large.

3-91. When the battery is connected to the sending end as shown in figure 3-

24, view A, a negative voltage moves down the line. This voltage charges each

capacitor, in turn, through the preceding inductor. Because Zi equals Z0, one-

to E/2 (view B). When the last capacitor in the line is charged, there is no voltage

across the last inductor and current flow through the last inductor stops. With no

current flow to maintain it, the magnetic field in the last inductor collapses and

forces current to continue to flow in the same direction into the last capacitor.

Because the direction of current has not changed, the capacitor charges in the

same direction, thereby increasing the charge in the capacitor. Because the

energy in the magnetic field equals the energy in the capacitor, the energy

transfer to the capacitor doubles the voltage across the capacitor. The last

capacitor is now charged to E volts and the current in the last inductor drops to

zero.

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