3-20
Figure 3-19.—Ac voltage applied to a line.
In this illustration the conventional lines of force represent the electric fields. For simplicity, the
magnetic fields are not shown. Points of charge are indicated by plus (+) and minus (-) signs, the larger
signs indicating points of higher amplitude of both voltage and current. Short arrows indicate direction of
current (electron flow). The waveform drawn below the transmission line represents the voltage (E) and
current (I) waves. The line is assumed to be infinite in length so there is no reflection. Thus, traveling
sinusoidal voltage and current waves continually travel in phase from the generator toward the load, or far
end of the line. Waves traveling from the generator to the load are called INCIDENT WAVES. Waves
traveling from the load back to the generator are called REFLECTED WAVES and will be explained in
later paragraphs.
Dc Applied to an Infinite Line
Figure 3-20 shows a battery connected to a circuit that is the equivalent of a transmission line. In this
line the series resistance and shunt conductance are not shown. In the following discussion the line will be
considered to have no losses.
