radio wave in paragraph 4 behaves in the same general manner as the waves of
As it leaves the antenna, it creates a continuous wave
disturbance which travels outward from the antenna at a constant velocity (a
free space. Of course, the term "free space" implies that the radio waves
are traveling in the atmosphere or a vacuum. The presence of hills, trees,
lakes, and other terrain features (natural and man-made) modifies the
effective radiation of an electromagnetic (radio) wave and distorts the
b. Quarter-wave antenna.
three-dimensional figure that looks somewhat like a doughnut with the
transmitting antenna in the center (Fig 6).
The quarter-wave, vertically
mounted antenna is omnidirectional (radiates in all directions).
vertically mounted antenna has minimum radiation off the top.
c. Half-wave antenna. The half-wave antenna, because of its physical
bidirectional (in two directions) and is at right angles (broadside) to the