U.S. Marine Corps Antenna Mcrp 6 22D Operating Instructions

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advantage based on polarization will be determined by the polariza-
tion of possible sources of interference. In deciduous forests the
sources are evenly divided between vertical and horizontal. In
mature coniferous forests the sources are predominately vertical, so
horizontal polarization has an advantage.
Power and Signal Lines
Distribute power and signal lines to eliminate and avoid crossovers.
If power and signal lines must cross, arrange them so...

Appendix A
GLOSSARY
Section I
Acronyms and Abbreviations
AM..............................................................amplitude modulationn
C.......................................................................................centigrade
CIS..................................communications and information systems
cm....................................................................................centimeter
COMSEC.................................................communications security...

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kHz.....................................................................................kilohertz
km.....................................................................................kilometer
kW........................................................................................kilowatt
LOS................................................................................line of sight...

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VHF..................................................................very high frequency
VHF-LOS.....................................very high frequency line of sight
VSWR..................................................voltage standing-wave ratio
W...............................................................................................watt 

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Section II
Definitions
A
alternating current—Current that is continually changing in mag-
nitude and periodically in direction from a zero reference level.
Also called AC.
amplification—The process of increasing the strength (current,
voltage, or power) of a signal.
amplitude—The level of an audio or other signal in voltage or cur-
rent. The magnitude of variation in a changing quantity from its
zero value.
amplitude modulation—Modulation in which the...

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A-5
antenna gain—The effectiveness of a directional antenna as com-
pared to a standard nondirection antenna. It is usually expressed as
the ratio in decibels of standard antenna input power to directional
antenna input power that will produce the same field strength in the
desired direction. For a receiving antenna, the ratio of signal power
values produced at the receiver input terminals is used. The more
directional an antenna is, the higher is its...

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baud—The number of times per second the carrier signal changes
value.
bidirectional—In two directions, usually opposite.
blob—Small areas of the atmosphere where temperatures and pres-
sure differences produce conditions suitable for the refraction of
radio waves.
broadband antenna—An antenna capable of operation over a
wide band of frequencies
C
cable connectors—Fittings for cable ends which permit rapid con-
nection and disconnection with equipment...

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communications circuit—The means by which information is
transferred between two or more places.
conductor—A material (usually metal) that has low resistance to
the flow of electrical current. A wire, cable, or other object capable
of carrying electric current. Good conductors are made of metals
such as silver, copper, and aluminum.
connections—Points at which two or more conductors are brought
into contact.
counterpoise—A conductor or system of...

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dielectric—A material that does not conduct electricity, such as
rubber or glass, i.e. an insulator.
diffraction—The process by which electromagnetic waves are bent
so that they appear behind an obstruction.
dipole antenna—A center-fed wire antenna whose conductors are
in a straight line.
directional antenna—An antenna designed to transmit and receive
RF energy in a specific direction(s).
direct waves—Waves which propagate in a straight line from the...

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A-9
the electromagnetic spectrum; the means by which energy is trans-
mitted from one place to another.
end-fed—An antenna whose power is applied to one end rather
than at some point between the ends.
F
fading— A periodic decrease in received signal strength.
feedpoint impedance—Impedance that is measured at the input
terminals of an electrical device such as an antenna.
fields—Regions in which each point has a value of a physical quan-
tity (voltage,...