Figure 16.
Measuring Standing Waves of Current.
28. The impedance varies along a mismatched line.
a. The impedance at any point on a transmission line is the ratio of
the voltage to the current at that point.
Figure 16 shows that the
impedance varies along a shorted line.
This happens because the waves
reflected by the short cause the voltage and current to vary.
Part A of
Figure 17 shows the standing waves of voltage and current along a line which
is one wavelength long. The voltage is minimum and the current maximum at
the shorted end.
The impedance at the shorted end is zero.
One-quarter
wavelength back from the short toward the generator, the impedance is
maximum because of the maximum voltage and minimum current at that point. A
half wavelength back from the short, the impedance is minimum again.
20
Previous Page
