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

Antenna Handbook ____________________________ 
4-35
Characteristics are—
Figure 4-27. 100-Foot Sloping Wire (Vertical Pattern). Frequency range:Depends on wire length/configura-
tion
Polarization:Vertical
Power capability:Determined by terminating resistor
Radiation pattern
Azimuthal (bearing):Bidirectional for unterminated
Directional for terminated
Vertical (take-off angle):See figure 4-27 and figures 4-28 and
4-29 on page 4-36TAKE-OFF ANGLE10°10°20°
20° 30°30° 40°40° 50°50° 60°60° 70°70° 80°80°...

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MCRP 6-22DTAKE-OFF ANGLE10°10°20°
20° 30°30° 40°40° 50°50° 60°60° 70°70° 80°80° 90°151050-5-10-51015dBi  3 MHz9 MHzFigure 4-28. 250-Foot Sloping Wire (Vertical Pattern).TAKE-OFF ANGLE10°10°20°
20° 30°30° 40°40° 50°50° 60°60° 70°70° 80°80° 90°151050-5-10-51015dBi
  3 MHz9 MHzFigure 4-29. 234-Foot Sloping Wire (Vertical Pattern). 

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4-37
Vertical Half-Rhombic
The vertical half-rhombic antenna is a version of the long wire
antenna that uses a single center support (see fig. 4-30).  Easily con-
structed, this antenna has a narrow width (as wide as the center sup-
port guys), which allows several to be installed in a relatively
narrow area. The vertical half-rhombic antenna radiates a medium-
to low-angle signal, making it a good choice for medium- to long-
range sky wave circuits....

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MCRP 6-22D
The vertical half-rhombic uses a single wire feed either through a
coupler or a balun (12 to 1). One of the two terminals of the coupler
or balun is attached to the antenna, while the other terminal is
grounded. Like other terminated antennas, the terminating resistor
(600 ohms) should be able to handle one-half of the transmitter’s
power output. Terminators can be procured or fabricated locally
(100-watt, 106-ohm resistor).
The orientation of this...

Antenna Handbook ____________________________ 
4-39TAKE-OFF ANGLE10°10°20°
20° 30°30° 40°40° 50°50° 60°60° 70°70° 80°80° 90°151050-5-10-51015dBi  3 MHz9 MHzFigure 4-31. 50-Foot Vertical Half-Rhombic (Vertical Pattern),
500 Feet Long.TAKE-OFF ANGLE10°10°20°
20° 30°30° 40°40° 50°50° 60°60° 70°70° 80°80° 90°151050-5-10-51015dBi
  3 MHz9 MHzFigure 4-32. 50-Foot Vertical Half-Rhombic (Vertical Pattern),
1,000 Feet Long. 

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MCRP 6-22D
HF NVIS COMMUNICATIONS
NVIS propagation is simply sky wave propagation that uses anten-
nas with high-angle radiation and low operating frequencies. Just as
the proper selection of antennas can increase the reliability of a
long- range circuit, short-range communications also require proper
antenna selection. NVIS propagation is one more weapon in the
communicator’s arsenal.
To communicate over the horizon to an amphibious ship on the
move, or to a...

Antenna Handbook ____________________________ 
4-41
ground wave and long-range sky wave interference. Antennas used
for NVIS propagation need good high take-off angle radiation with
very little ground wave radiation (see fig. 4-33). 
Using the HF antenna selection matrix (table 4-4 on page 4-8), the
AS-2259/GR and half-wave dipole are the only antennas listed that
meet the requirements of NVIS propagation. While the inverted vee
and inverted L antennas have high-angle radiation, they also can
have strong...

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MCRP 6-22D
The dipole antenna pattern is illustrated in figures 4-11 and 4-12 on
page 4-17 and figure 4-13 on page 4-19. The patterns for 3 and 9
MHz show that large amounts of energy are directed up in the 60°
to 90° range. Also, the pattern is the same on both sides of the 90°
line. This means that a low dipole would be a good antenna for
NVIS propagation. The pattern at 18 MHz is not important because
NVIS propagation normally does not use frequencies much...

Antenna Handbook ____________________________ 
4-43  WARNINGTHE WIRE MUST BE PROTECTED SO THAT MARINES DO
NOT WALK INTO IT. IT CARRIES ENOUGH RF ENERGY DUR-ING TRANSMISSION TO CAUSE SEVERE INJURIES.
When using a manpack radio like the AN\PRC-104, the whole radio
can be rotated so that the 8-foot antenna is tilted at least 30°.
Because of the antenna’s flexibility, it will need support on the far
end. This support must be a good insulator. Ensure that Marines
keep clear of the antenna. Characteristics...

Chapter 5
VHF and UHF Antenna Selection
FREQUENCIES
The VHF portion of the radio spectrum extends from 30 to 300
MHz. The UHF range reaches from 300 to 3,000 MHz (3 GHz).
Both frequency ranges are extremely useful for short-range (less
than 50 km) communications. This includes point-to-point, mobile,
air-to-ground, and general purpose communications. A wavelength
at these frequency ranges is considerably shorter than those in the
HF range, and simple antennas are much smaller. 
Because the VHF and UHF...