(c) RF energy meets a high Z at the opening of the quarter-wave
(d) Quarter-wave section also acts as a sturdy mechanical support
for the main line.
(2) Figure 20, Part B.
(a) A shorted quarter-wave
(b) The oscillator is tuned by adjusting the movable shorting bar.
(3) Figure 20, Part C.
(a) An antenna is usually balanced.
impedance and voltage with respect to ground.
(b) A coaxial line is unbalanced.
The outside conductor is at
(c) The bazooka removes the ground potential at the point where
the antenna is connected to the coaxial line.
(4) Figure 20, Part D.
(a) An open-end, quarter-wave section sets up a low Z at AB to the
(b) RF energy at the fundamental frequency passes to the antenna.
(c) The filter becomes a half-wave section at the second harmonic.
It sets up a high impedance at AB.
(d) The second harmonic does not pass on to the antenna.
a. The half-wave section of a line is really an extension of the
So, if you understand how the quarter-wave section
works, you will have little difficulty with the half-wave section. Figure
21 shows the standing-wave and impedance variations on a half-wave section
of line. Notice that whatever conditions appear on the load end of the line
are repeated at the generator or source end. For example, look at Part A of