2.5 Reflection of DC voltage in Transmission lines
47
Figure 2.5-2 The switch is closed and the voltage wave starts propagating down the transmission line
Since Z
s
= Z
0
, one-half of the applied voltage (E/2) will appear across the internal battery impedance,
Z
s
, and one-half across the impedance of the line, Z
0
. This voltage "wave" applies a potential of E/2
across the first inductor-capacitor section and hence a current I flows through the inductor to
charge the respective capacitor up to a voltage equal to E/2 volts. This is again shown in Figure 2.5-2.
Once the first capacitor is charged, no further current will flow through it and, as the voltage wave
advances, the current I will flow through second inductor to charge the second capacitor up to a E/2
volts (Figure 2.5-3).
Figure 2.5-3 As the voltage wave advances, it charges up the second capacitor
This process continues as the voltage wave continues to travel down the line charging each capacitor
through the preceding inductor (Figure 2.5-4).
Figure 2.5-4 The voltage wave continues to travel down the line
E/2
E
I
E/2
Zero
Z
s
E
E/2
I
E/2 E/2
E
E/2
I
E/2 E/2 E/2
Conquer Radio Frequency
47 www.cadence.com/go/awr
