Figure 135.
Simple Dipole With a Reflector.
c. The reflector picks up energy from the driven elements and
reradiates it.
The reflector is placed .15 wavelength from the driven
element so that the fields cancel in the direction of the reflector and add
in the direction of the drivers.
Notice that most of the energy is
transmitted in one direction. If this same antenna is used as a receiving
antenna, it will pick up energy from the same direction.
9.
Adding a director also makes dipole antenna directional.
a. Another way of making a dipole antenna directional is to
add a
parasitic element called a director to the two conductors as shown in
Figure
136. The director is placed .1 wavelength from the driven elements,
and it
is a little shorter than one-half wavelength. The director picks up
energy
from the driven elements and reradiates it in such a way that the
energy
adds to the original radiation in the direction of the director.
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