-
Radio energy is transmitted through
which of the following mediums?
Space
-
Energy is transmitted from a transmitter
into space using which of the following
devices?
A transmitting antenna
-
Transmitted rf energy takes what form as
it is sent into space?
An electromagnetic field
-
The dimensions of a transmitting antenna
are determined by which of the following
factors?
Transmitted frequency
-
A device used to radiate or receive
electromagnetic wave energy is referred
to as a/an
antenna
-
An antenna that can be mounted to
radiate rf energy either vertically or
horizontally is classified as which of the
following types?
Hertz
-
A complete antenna system consists of
which of the following components?
- A feeder line, a coupling device, and
- an antenna
-
What component in an antenna system
transfers energy from the transmitter to
the antenna?
A feeder
-
The type, size, and shape of an antenna
are determined by which of the following
factors?
Power output of the transmitter, Transmitter frequency, and direction to the receiver.
-
Moving electric and magnetic fields in
space have what (a) phase and
(b) angular relationships?
In Phase and Perpendicular
-
What is the length of each half of the
wire for a dipole antenna?
1/4 wavelength
-
On a dipole antenna, the sinusoidal
variation in charge magnitude lags the
sinusoidal variation in current by what
amount?
1/4 cycle
-
On a standing wave, the points of high
current and voltage are identified by
which of the following terms?
Loops
-
The presence of standing waves indicates
which of the following conditions of an
antenna?
Resonance
-
The antenna property that allows the
same antenna to both transmit and
receive energy is
reciprocity
-
There is a ratio between the amount of
energy propagated in certain directions
by a directional antenna compared to the
energy that would be propagated in these
directions if the antenna were not
directional. This ratio is known as which
of the following antenna characteristics?
Gain
-
The polarization plane of the radiation
field is determined by which of the
following fields?
Electric field only
-
For best reception of a signal from a
horizontally polarized antenna, the
receiving antenna should be mounted so
that it has what relationship with the
transmitting antenna?
90 degrees
-
An electric field that rotates as it travels
through space exhibits what type of
polarization?
Elliptical
-
For ground-wave transmissions, what
type of polarization is required?
Vertical
-
For high-frequency operation, which of
the following antenna polarization
patterns is preferred?
Horizontally polarized
-
Omnidirectional transmission is obtained
from which of the following antennas?
Vertical half-wave
-
With an antenna height of 40 feet and a
transmitter frequency of 90 megahertz,
which of the following antenna radiation
patterns is best for transmitting over
bodies of water?
Vertically polarized
-
To select a desired signal and
discriminate against interfering signals
from strong vhf and uhf broadcast
transmissions, which of the following
actions should you take?
- Use a vertically polarized receiving
- antenna
-
A vertically mounted transmission line is
LEAST affected by which of the
following antenna radiation patterns?
Horizontally polarized
-
An antenna with which of the following
radiation resistance values will exhibit
reduced efficiency?
39 ohms
-
An isotropic radiator radiates energy in
which of the following patterns?
Omnidirectional
-
An ordinary flashlight is an example of
what type of radiator?
Anisotropic
-
The area enclosed by the radiation
pattern is the
lobe
-
Inserting an inductor or capacitor in
series with an antenna is one method of
electrically changing the electrical length
of an antenna. What is this method
called?
Loading
-
Many complex antennas are constructed
from what basic antenna?
The half-wave antenna
-
On an energized half-wave antenna,
which of the following electrical
conditions exist?
Voltage is maximum at the ends
-
Which of the following radiation patterns
is/are exhibited by a simple vertical
doublet antenna?
Nondirectional in the horizontal plane. And the directional in the vertical plane.
-
A method of feeding energy to a halfwave
antenna is to connect one end
through a capacitor to the output stage.
What is this method of feeding called?
End feed and voltage feed.
-
An antenna supplied by the center-feed
method is fed at what point?
Low voltage and high current.
-
The basic Marconi antenna has which of
the following characteristics?
- One-quarter wavelength and
- grounded at one end
-
The Marconi antenna behaves as a dipole
for which of the following reasons?
- An image antenna is formed by
- reflections from the ground
-
A series of conductors arranged in a
radial pattern and buried in the ground
beneath the antenna is referred to as a
ground screen
-
A folded dipole can be used instead of a
simple, center-fed dipole for which of the
following purposes?
Matching impedance
-
An antenna arrangement that has
elements aligned in a straight line is
referred to as what type array?
Unidirectional
-
To select a desired signal and
discriminate against interfering signals,
the receiving antenna should have which
of the following characteristics?
Be vertically polarized
-
Adding more elements to a collinear
antenna array produces which of the
following effects?
Increased gain
-
What is the maximum number of
elements ordinarily used in a collinear
array?
Four
-
Constructing a collinear array with
elements longer than 1/2 wavelength has
which of the following effects on antenna
characteristics?
Increased frequency range
-
In a two-element collinear array,
maximum gain is obtained when the
center-to-center spacing between the
ends of the elements is approximately
what electrical distance?
0.75 wavelength
-
Compared with collinear arrays,
broadside arrays have which of the
following advantages?
Sharper tuning
-
Optimum gain is obtained from a
broadside array when the spacing of its
elements is which of the following
distances?
One-half wavelength
-
An end-fire array physically resembles
the collinear array except that it is more
compact. What disadvantage does the
endfire array possess?
It has low radiation resistance
-
What is the range of electrical spacing
between the elements of an end-fire
array?
1/8 to 1/4 wavelength
-
Assuming that the elements are correctly
spaced, the directivity of an end-fire
array may be increased by which of the
following actions?
Increasing the number of elements
-
A unidirectional pattern can be obtained
from an end-fire array by using what
phase relationship between the energy
fed to adjacent elements?
90º
-
The ratio of energy radiated by an array
in the principal direction of radiation to
the energy radiated in the opposite
direction describes which of the
following relationships?
Front-to-back ratio
-
The Yagi antenna is an example of what
type of antenna array?
Multielement parasitic
-
The addition of parasitic elements to the
Yagi antenna has which of the following
effects on antenna characteristics?
Increased gain, Narrower beam width, and narrower frequency response.
-
An antenna which is designed especially
for vertically-polarized ground waves at
low frequencies is the
Beverage antenna
-
What is the phase relationship of the
signals that feed the V antenna?
180º
-
A rhombic antenna is essentially a
combination of which of the following
antennas?
Two collinear arrays in parallel
-
A rhombic antenna has which of the
following advantages?
Simple construction, wide frequency range, and noncreitical adjustment.
-
The principal disadvantage of the
rhombic antenna is its
large antenna site
-
The unidirectional radiation pattern of
the rhombic antenna is caused by which
of the following antenna characteristics?
Termination resistance
-
Horizontal half-wave antennas mounted
at right angles to each other in the same
horizontal plane make up which of the
following antennas?
Turnstile
-
The most common means of obtaining a
low-radiation angle from a vertical
quarter-wave antenna is by what
procedure?
Adding a ground plane
-
A corner reflector antenna is used for
which of the following purposes?
To produce a unidirectional pattern
-
If a corner-reflector antenna is
horizontally polarized, its radiation
pattern will take on what shape?
A narrow beam in the vertical plane
-
When radio or radar antennas are
energized by transmitters, you must not
go aloft until which of the following
requirements are met?
- A working aloft "chit" has been filled
- out and signed by proper authority
-
A transmission line is designed to perform which of the following functions?
Guide electrical energy from point to point
-
All transmission lines must have two ends,the input end and the output end. What other name is given to the input end?
Generator end
-
A measurement of the voltage to current ratio (Ein/I in) at the input end of a transmission line is called the
input impedance
-
Which of the following lines is NOT a transmission medium?
Load line
-
Electrical power lines are most often made of which of the following types of transmission lines?
Two-wire open line
-
Uniform capacitance throughout the length of the line is an advantage of which of the following transmission lines?
Shielded pair
-
What is the primary advantage of a rigid coaxial line?
Low radiation losses
-
Which of the following wave-guides is seldom used because of its large energy loss characteristics?
Dielectric
-
To some degree, transmission lines always exhibit which of the following types of losses?
I2R
-
Skin effect is classified as which of the following types of loss?
Copper
-
What transmission-line loss is caused by magnetic lines of force not returning to the conductor?
Radiation
-
The conductance value of a transmission line represents which of the following values?
Expected value of current flow through the insulation
-
Electrical constants in a transmission line are distributed in which of the following ways?
Along the length of the line
-
Leakage current in a two-wire transmission line is the current that flows through what component?
The insulator
-
Conductance is the reciprocal of what electrical property?
Resistance
-
A transmission line that has current flowing through it has which, if any, of the following fields about it?
Both electric and magnetic fields
-
Maximum transfer of energy from the source to the transmission line takes place when what impedance relationship exists between the source and the transmission line?
When the load impedance equals source impedance
-
The characteristic impedance (Z0) of a transmission line is calculated by using which of the following ratios?
E to I at every point along the line
-
For a given voltage, what determines the amount of current that will flow in a transmission line?
Characteristic impedance
-
When should lumped values for transmission-line constants be used to calculate characteristic impedance?
When the line is short compared to one wavelength
-
In actual practice, the characteristic impedance of a transmission line is usually within which of the following resistance ranges?
50 to 600 ohms
-
The input impedance of a transmission line is affected by which of the following properties?
Radiation loss, Series inductance, and parallel capacitance
-
When a dc voltage is applied to a transmission line and the load absorbs all the energy, what is the resulting relationship between current and voltage?
They are evenly distributed along the line
-
The initial waves that travel from the source to the load of a transmission line are referred to as what type of waves?
Incident
-
Waves that travel from the output end to the input end of a transmission line are referred to as what type of waves?
Reflected
-
The instantaneous voltage on an infinite transmission line can be plotted against time by using which of the following instruments?
An oscilloscope
-
On an infinite transmission line with an ac voltage applied, which of the following is an accurate description of the effective voltage distribution along the line?
Voltage is constant at all points
-
The velocity of propagation on a transmission line is controlled by which of the following line characteristics?
Capacitance and inductance
-
The total charge on a transmission line is equal to the current multiplied by which of the following factors?
Time
-
With only capacitance and inductance of the line given, the time (T) required for a voltage change to travel down a transmission line can be found by what formula? The characteristic impedance for an infinite transmission line can be figured using which of the following ratios?
T - L/C 1/2
-
The characteristic impedance for an infinite transmission line can be figured using which of the following ratios?
Input voltage to input current
-
When a transmission line is not terminated in its characteristic impedance (Z0), what happens to the incident energy that is NOT transferred to the load?
It is returned along the transmission line
-
In an open-ended transmission line with an ac signal applied, what is the phase relationship between the incident and reflected voltage waves?
180 degrees out of phase
-
The resultant of the incident and reflected voltage waves is called the standing wave.Its value is figured by using which of the following procedures?
Algebraically adding the instantaneous values of the two waveforms
-
At the end of an open-ended transmission line, which, if any, of the following voltage waves is at its maximum value?
Incident
-
On a transmission line that is carrying an ac signal, what is the relative value of the resultant voltage wave 1/4 wavelength from the open end?
Zero
-
Which of the following conditions exist at the end of a shorted transmission line?
Minimum voltage and maximum current
-
Transmission line is considered to be nonresonant (flat) when it is terminated in which of the following ways?
In an impedance equal to Z0
-
Of the following terms, which one is used for the nonresonant transmission line?
An untuned line
-
A transmission line that is resonant is sometimes referred to as which of the following types of lines?
Tuned
-
A short-circuited section of transmission line that is an odd number of quarter wavelengths long shows the same characteristics as which of the following devices?
A parallel-resonant circuit
-
Which of the following sections of transmission line can be used as a parallel resonant circuit?
A shorted 1/4-wavelength section
-
A generator connected to an open-ended line greater than 1/4 wave-length but less than 1/2 wave-length senses which of the following circuit component characteristics?
Inductive reactance
-
Which of the following conditions of current (I) and impedance (Z) exist at even quarter-wave points on a shorted transmission line?
High I, low Z
-
What is the maximum distance, in wavelengths (), between adjacent zero current points on an open-circuited line?
1 wavelenth
-
When a line is terminated in a capacitance,the capacitor performs which, if any, of the following circuit actions?
It reflects all the energy
-
When a transmission line is terminated in an inductive reactance, which, if any, of the following phase shifts takes place with respect to the current and voltage?
Both voltage and current are phase-shifted
-
When a transmission line is terminated in a resistance greater than Z0, which of the following conditions exist?
The end of the line appears as an open circuit
-
On a transmission line, reflections begin at which of the following locations?
At the load
-
The ratio of maximum voltage to minimum voltage on a transmission line is referred to as the
vswr
-
Which of the following ratios samples the magnetic field along a line?
Iswr
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