b. The incident wave of RF energy travels down the line in the form of
voltage and current waves. When the RF energy reaches the open end of the
line, the current wave drops to zero because it can go no further.
The
magnetic field that is always associated with the flow of current collapses,
developing an induced voltage on the line.
The induced voltage tries to
keep current flowing in the same direction as before. But, there is no line
extending to the right on which the current can flow. The only place for
the current to go is back to the source. The energy traveling back to the
source is called a reflected wave as shown in Part B of Figure 10.
Figure 10. Formation of Standing Waves.
20. There are two waves traveling on a transmission line.
a. So, now we have two waves traveling on the transmission line in
opposite directions. One, the incident wave, is traveling from the source
out to the open end of the line.
The other, the reflected wave, is
traveling back to the source from the open end of the line. This condition
is shown in Part C of Figure 10.
Notice that the phase of the reflected
current wave is 180 degrees out of phase with the incident current wave.
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