___________________________________________________ Principles of Transmission Lines
Figure 3-25. Reflection from a Short-Circuited Line
3-100. In most cases where RF lines are used, the voltages applied to the
sending end are AC voltages. The action at the receiving end of the line is
exactly the same for AC as for DC. In the open-ended line, as shown in figure
3-26, view A, the generated AC voltage is distributed along the line, shown in
view B. This voltage is distributed in such a way that as each instantaneous
voltage arrives at the end, it is reflected with the same polarity and amplitude.
When AC is used, this reflection is in phase. Each of the reflected voltages
travels back along the line until it reaches the generator. If the generator
is absorbed and not reflected again. Now two voltages are on the line.