TC 9-64 _________________________________________________________________________
spaced, concentric circles. In this example, they are numbered successively
from 1 to 10 from the center out. These circles are used to indicate the
magnitude of the radiation.
4-63. The advantages of the polar-coordinate graph are immediately evident.
The source, which is at the center of the observation circles, is also at the
center of the graph. By looking at a polar-coordinate plot of a radiation
pattern, you can immediately see the direction and strength of radiation put
out by the source. Therefore, the polar-coordinate graph is more useful than
the rectangular-coordinate graph in plotting radiation patterns.
Anisotropic Radiation
4-64. Most radiators emit (radiate) stronger radiation in one direction than
in another. A radiator such as this is referred to as anisotropic. An example of
an anisotropic radiator is an ordinary flashlight. The beam of the flashlight
lights only a portion of the space surrounding it. If a circle is drawn with the
flashlight as the center, as shown in figure 4-12, view B, the radiated light
can be measured at different positions around the circle. Again, as with the
isotropic radiator, all positions are the same distance from the center, but at
different angles. However, in this illustration the radiated light is measured
at 16 different positions on the circle.
4-18
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