Standing waves at the resonant frequency points of an open- or short-circuited transmission line produce unusual effects. When the signal frequency is such that exactly 1/2 wave or some multiple thereof matches the line's length, the source "sees" the load impedance as it is. The following pair of illustrations shows an open-circuited line operating at 1/2 (Figure below)
and 1 wavelength (Figure below) frequencies:...
Impedance Transformation
and 1 wavelength (Figure below) frequencies:...
Impedance Transformation
