Lesson 2/Learning Event 1
LESSON 2
CALCULATE ANTENNA LENGTH
TASK:
Calculate
antenna
length,
and
identify
antenna
properties.
CONDITIONS:
Given this lesson material, pencil, paper and without
supervision.
STANDARDS:
Demonstrate
competency
of
the
task
skills
and
knowledge by correctly responding to 70 percent of the
multiple-choice
test
covering
calculating
antenna
length and identifying antenna properties.
Learning Event 1:
CHARACTERISTICS OF ANTENNAS.
Half-Wave and Quarter-Wave Antennas
1.
Basic Theory.
a. The antenna is part of the electrical circuit of the
transmitter and receiver.
As mentioned earlier, radio waves travel
in free space at 300,000,000 meters per second.
Our antenna is not
in free space but erected over and near terrain features which affect
antenna length. For that reason, the physical length of the antenna
is shorter than the electrical length.
b. There are several factors which cause the antenna to be
physically shorter.
As the diameter of the antenna wire increases,
the velocity or speed of the radio waves is slowed, decreasing
antenna length. See Figure 29.
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