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

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MCRP 6-22D
G
gain—The increase in signal strength that is produced by an ampli-
firer.
generator—A device that changes mechanical energy into electri-
cal energy.
ground—A very large semiconductive surface (the Earth) or a
smaller highly conductive surface.
ground radials—Wires on or in the earth to improve its conductiv-
ity near the antenna.
ground screen—A wire mesh ground plane.
ground wave—A radio wave that travels along the Earth’s surface
rather than...

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horizontal dipole—A dipole constructed parallel to the Earth’s sur-
face.
horizontal pattern—The horizontal cross-section of an antenna’s
three-dimensional radiation pattern.
horizontal polarization—Transmission of radio waves in such a
way that the electric lines of force are horizontal (parallel to the
Earth’s surface).
I
impedance—The total opposition offered by a circuit or compo-
nent to the flow of alternating current.
impedance match—The...

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MCRP 6-22D
inverted vee antenna—A half-wave dipole erected in the form of
an upside-down vee, with the feed point at the apex. It is essentially
omnidirectional, and is sometimes called a “dropping doublet.”
ionization—The process where radiation and particles from the
Sun make some of the Earth’s atmosphere partially conductive.
ionosphere—A partially conducting region of the Earth’s atmo-
sphere between 50 kms and 400 kms high.
L
lambda—Greek lower case letter...

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lowest usable frequency—The lowest frequency that will not be
absorbed by the ionosphere or smothered by atmospheric noise.
Also called LUF.
M
maximum usable frequency—The highest frequency for a given
elevation angle that will reflect from an ionospheric layer. Also
called MUF.
megahertz—One million cycles per second. Also called MHz.
modulate—To change the output of a transmitter in amplitude
phase, or frequency in accordance with the information to...

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MCRP 6-22D
out of phase—Two alternating quantities not passing through cor-
responding values at the same time (e.g., if the current in a circuit
reaches its maximum value before or after the applied voltage does,
the current is out of phase with the voltage).
P
path loss—The ratio of received power to transmitted power.
polarization—The direction of the electric field of a radiated wave
relative to the surface of the Earth (vertical, horizontal, linear, and...

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R
radiate—To transmit RF energy.
radiation—Energy that moves through space as electromagnetic
waves.
radiation patterns—A chart of relative radiation intensity (or
power) versus direction.
radio frequency—Any frequency of electrical energy capable of
propagation into space (usually above 20 kHz). Also called RF.
radio horizon—The greatest distance on the Earth at which a trans-
mitted wave can be received by the direct path from a transmitter
located on...

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MCRP 6-22D
reflection—The turning back of a radio wave from an object or the
surface of the Earth.
reflector type antenna—An antenna placed in front of a conduct-
ing surface (reflector) for the purpose of increasing radiation in one
direction, at the expense of radiation in other directions.
refraction—The bending, or changing direction, of a radio wave
passing into or through layers of the atmosphere or the ionosphere
that have different density (dielectric...

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shortened dipole—A dipole antenna made to resonate at a lower
frequency by use of a coil.
signal—A radio wave that contains the transmitted message.
signal loss—The amount of signal power lost between the transmit-
ter and receiver.
signal-to-noise ratio—The power intensity of the signal compared
to that of the noise.
skip distance—The distances on the Earth’s surface between the
points where a radio wave sky wave leaves the antenna and is suc-...

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sunspots—Activity on the Sun’s surface which is seen as a series of
blemishes that vary in size, number, and location.
T
take-off angle—The angle measured from the Earth’s surface or
horizontal up to the direction of propagation towards the iono-
sphere.
transistor—A minute electronic device that permits a small current
to control the flow of a larger current.
transmission line—A conductor that transfers radio frequency RF
energy from the transmitter...

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U
ultrahigh frequency—Frequencies between 300 and 3,000 MHz.
unbalanced transmission line—A transmission line one of whose
conductors is grounded.
unidirectional—In one direction only.
V
vee antenna—Two long-wire antennas connected to form a vee.
velocity—The speed of a radio wave through the dielectric medium
it is in.
vertical dipole—A balanced or dipole antenna oriented vertically.
vertical polarization—Transmission of radio waves in such a way
that...