a. Advantages of vertical polarization.
A simple vertically mounted
antenna provides omnidirectional (all directions) communications.
The
advantages of using vertically polarized antennas are as follows:
Best for communicating with a radio mounted in a moving vehicle.
Provide a stronger signal at frequencies up to 50 MHz when antenna
lengths are limited (10 feet or less).
Less affected by
from
aircraft
flying
over
the
transmission path.
Less interference produced or picked up from strong VHF and UHF
broadcasts. (Commercial television and radio stations [VHF and UHF
broadcasting stations] use horizontally polarized antennas.)
b. Advantages of horizontal polarization.
A simple horizontally
mounted half-wave antenna is bidirectional.
The advantages of using
horizontally polarized antennas are as follows:
It is bidirectional--accepts signals from all directions except the
direction in line with the ends of the antenna.
It is less likely to pick up man-made interference (other tactical
radios which use vertically polarized antennas and electrical motors
and generators).
When located near dense forests, it suffers lower output power
losses than vertically polarized antennas (especially above 100
MHz).
Small changes in antenna location do not cause large variations in
field intensity when antennas are located among trees or near
buildings.
PRACTICE EXERCISES:
16. T
F
The transmission requirements of field artillery radios are
usually accomplished by means of sky waves.
17. T
F
Line-of-sight radio transmission is accomplished
by
the
direct wave component of propagated ground waves.
18. T
F
Regardless of the type of antenna polarization (horizontal
or vertical), the direction of travel of radiated radio
waves is considered to be parallel to the surface of the
earth.
14
Previous Page
