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2-68. Radar range is determined as a function
of which of the following measures?
1. Pulse travel time
2. Elevation angle of the antenna
3. Distance to the horizon
4. Angular velocity of the energy
2-69. The parabolic reflector is often used
because it produces a radiation pattern
with which of the following antenna
characteristics?
1. Omnidirectional
2. Highly directive
3. Many equal lobes
4. Spherical wavefronts
2-70. In a lens antenna, what is the purpose of
the collimating lens?
1. It produces spherical wavefronts
2. It produces an omnidirectional pattern
3. It forces parallel segments of the
wavefront into spherical paths
4. It forces radial segments of the
wavefront into parallel paths
2-71. A lens antenna which accelerates some
portion of the wavefronts so that all
wavefronts exit the lens at the same time
is referred to as the
1. metallic delay lens
2. waveguide-type lens
3. loaded microwave lens
4. dielectric delay lens
2-72. In a delay-type lens, the amount of delay
in the phase of the wave passing through
the lens is determined by which of the
following characteristics?
1. The dielectric constant of the lens
2. The characteristic impedance of the
lens
3. The physical size of the lens
4. All of the above
2-73. What is/are the basic type(s) of antenna
array(s) in common use?
1. Driven only
2. Parasitic only
3. Parasitic and driven
2-74. In a frequency-sensitive antenna, the
physical length of the serpentine section
and its relationship to the wavelength of
the applied energy determines which of
the following characteristics?
1. Output power
2. Beam narrowness
3. Antenna efficiency
4. Direction of the beam
2-75. In a horizontal-slot antenna, the
polarization of the energy is radiated in
what direction?
1. Vertical
2. Spherical
3. Horizontal
4. Omnidirectional
