Lesson 1/Learning Event 1
LESSON 1
IDENTIFY CHARACTERISTICS OF WAVE PROPAGATION
TASK:
Identify the characteristics of wave propagation.
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 identification of the
characteristics of wave propagation.
(This objective
supports SM task number and title 113-596-7056, Direct
Installation of a Doublet Antenna.)
Learning Event 1:
GROUND WAVES.
1.
In 1887, Henrich Hertz demonstrated that electromagnetic energy
could be sent out into space in the form of radio waves. Radio waves
travel at the speed of light in free space, 186,000 miles per second,
or 300,000,000 meters per second.
Free space implies that radio
waves travel through empty space or a vacuum.
In actual practice,
radio energy travels slightly slower because of the presence of
trees, hills, lakes, and the air it travels through.
If we have a
radio frequency of 1,000,000 cycles (1 MHz) per second, its full wave
We will use the Greek letter lambda to
length is 984 feet.
represent wave length.
V (velocity) will represent the speed of
radio waves. F (frequency) represents the assigned frequency.
= V/F
Since: = V/F = 300,000,000 meters per second/1,000,000 HZ (1MHz)
= 300 meters = one wave length
one meter equals 3.2808 feet
converting into feet = 300 X 3.2808 = 984 feet = one wave length =
then one half wave length /2 = 984/2 = 492 feet
1
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