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4-66. The principal disadvantage of the
rhombic antenna is its
1. poor directivity
2. large antenna site
3. low antenna voltage
4. high-frequency inefficiency
4-67. The unidirectional radiation pattern of
the rhombic antenna is caused by which
of the following antenna characteristics?
1. Size
2. Shape
3. Termination resistance
4. Frequency of the input energy
4-68. Horizontal half-wave antennas mounted
at right angles to each other in the same
horizontal plane make up which of the
following antennas?
1. Rhombic
2. Flat-top
3. Turnstile
4. Ground-plane
4-69. The most common means of obtaining a
low-radiation angle from a vertical
quarter-wave antenna is by what
procedure?
1. Decreasing power
2. Increasing frequency
3. Adding a ground plane
4. Rotating the antenna to a horizontal
plane
4-70. A corner reflector antenna is used for
which of the following purposes?
1. To decrease frequency range
2. To increase frequency range
3. To produce a unidirectional pattern
4. To produce an omnidirectional
pattern
4-71. If a corner-reflector antenna is
horizontally polarized, its radiation
pattern will take on what shape?
1. A narrow beam in the horizontal
plane
2. A narrow beam in the vertical plane
3. A beam similar to a half-wave dipole
in the horizontal plane
4. A beam similar to a half-wave dipole
with a reflector in the vertical plane
4-72. When radio or radar antennas are
energized by transmitters, you must not
go aloft until which of the following
requirements are met?
1. A safety harness has been issued to
you
2. All transmitters are secured and
tagged
3. A working aloft "chit" has been filled
out and signed by proper authority
4. Each of the above
