The half-wave section of transmission line.

(c) RF energy meets a high Z at the opening of the quarter-wave

section.

(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

section

has

the

properties

of

a

(b) The oscillator is tuned by adjusting the movable shorting bar.

(3) Figure 20, Part C.

(a) An antenna is usually balanced.

Each

side

has

the

same

impedance and voltage with respect to ground.

(b) A coaxial line is unbalanced.

The outside conductor is at

ground potential.

(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

fundamental frequency.

(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.

31. The half-wave section of transmission line.

a. The half-wave section of a line is really an extension of the

quarter-wave section.

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

Figure 21 which shows the voltage,

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