WorksheetsTransmission Lines Quiz
Total questions: 182
Worksheet time: 2hrs 31mins
The most commonly used transmission line is a
Two-wire balance line
Single wire
Three-wire line
Coax
The characteristic impedance of a transmission line does not depend upon its
Length
Conductor diameter
Conductor spacing
None of the above
Which of the following is not a common transmission line impedance?
50 Ω
75 Ω
120 Ω
300 Ω
For maximum absorption of power at the antenna, the relationship between the characteristic impedance of the line Z O and the load impedance Z l should be
Z 0 = Z 1
Z 0 > Z 1
Z 0 < Z 1
Z 0 = 0
The mismatch between antenna and transmission line impedances cannot be corrected for by
Using an LC matching network
Adjusting antenna length
Using a balun
Adjusting the length of transmission line
A pattern of voltage and current variations along a transmission line not terminated in its characteristic impedance is called
An electric field
Radio waves
Standing waves
a magnetic field
The desirable SWR on a transmission line is
0.
1.
2.
Infinity
A 50 Ω coax is connected to a 73 Ω antenna. The SWR is
0.685.
1.
1.46.
2.92.
The most desirable reflection coefficient is
0.
0.5.
1.
Infinity
A ratio expressing the percentage of incident voltage reflected on a transmission line is known as the
Velocity factor
standing wave ratio
Reflection coefficient
Line efficiency
The minimum voltage along a transmission line is 260 V, while the maximum voltage is 390 V. The SWR is
0.67
1.0
1.2
1.5
Three feet is one wavelength at a frequency of
100 MHz
164 MHz
300 MHz
328 MHz
At very high frequencies, transmission lines are used as
Tuned circuit
Antennas
Insulators
Resistors
A shorted quarter-wave line at the operating frequency acts like a(n)
Series resonant circuit
Parallel resonant circuit
Capacitors
Inductor
A shorted half-wave line at the operating frequency acts like a(n)
Capacitors
Inductor
Series resonant circuit
Parallel resonant circuit
A popular half-wavelength antenna is the
Ground plane
End-fire
Collinear
Dipole
The length of a doublet at 27 MHz is
8.67 ft.
17.33 ft
18.2 ft
34.67 ft
A popular vertical antenna is the
Collinear
Dipole
Ground Plane
Broadside
The magnetic field of an antenna is perpendicular to the earth. The antenna’s polarization
Is vertical
Is horizontal
Is circuit
Cannot be determined from the information given
An antenna that transmits or receives equally well in all directions is said to be
Omnidirectional
Bidirectional
Unidirectional
Quasidirectional
The horizontal radiation pattern of a dipole is a
Circle
Figure eight
Clover left
Narrow beam
the length of a ground plane vertical at 146 MHz is
1.6 ft.
1.68 ft.
2.05 ft.
3.37 ft.
The impedance of a dipole is about
50 Ω
73 Ω
93 Ω
300 Ω
A directional antenna with two or more elements is known as a(n)
Folded dipole
Ground plane
Loop
Array
The horizontal radiation pattern of a vertical dipole is
Figure eight
Circle
Narrow beam
Clover leaf
In a Yagi antenna, maximum direction of radiation is toward the
Director
Driven element
Reflector
Sky
Conductors in multielement antennas that do not receive energy directly from the transmission line are known as
Parasitic elements
Driven elements
The boom
Receptors
A coax has an attenuation of 2.4 db per 100 ft. The attenuation for 275 ft is
2.4 dB
3.3 dB
4.8 dB
6.6 dB
An antenna has a power gain of 15. The power applied to the antenna is 32 W. The effective radiated power is
15 W
32 W
120 W
480 W
Which beamwidth represents the best antenna directivity
70
120
190
280
The radiation pattern of collinear and broadside antennas
Omnidirectional
Bidirectional
Unidirectional
Clover-leaf shape
Which antenna has a unidirectional radiation pattern and gain
Dipole
Ground plane
Yagi
Collinear
A wide-bandwidth multielement driven array is the
End-fire
Log-periodic
Yagi
Collinear
Ground-wave communications is most effective in what frequency range?
300 kHz to 3 MHz
3 to 30 MHz
30 to 300 MHz
Above 300 MHz
The ionosphere causes radio signals to be
Diffused
Absorbed
Refracted
Reflected
The ionosphere has its greatest effect on signals in what frequency range?
300 kHz to 3 MHz
3 to 30 MHz
30 to 300 MHz
Above 300 MHz
The type of radio wave responsible for long-distance communications by multiple skips is the
Ground wave
Direct wave
Surface wave
Sky wave
Microwave signals propagate by way of the
Direct wave
Sky wave
Surface wave
Standing wave
The line-of-sight communications is not a factor in which frequency range?
VHF
UHF
HF
Microwave
A microwave-transmitting antenna is 550 ft high. The receiving antenna is 200 ft high. The maximum transmission distance is
20 mi.
33.2 mi.
38.7 mi.
53.2 mi.
To increase the transmission distance of a UHF signal, which of the following should be done Above 300 MHz?
Increase antenna gain
Increase antenna height
Increase transmitter power
Increase receiver sensitivity
A coax has a velocity factor of 0.68. What is the length of a half wave at 30 MHz?
11.2 ft
12.9 ft
15.6 ft
16.4 ft
Which transmission line has the lowest attenuation?
Twin lead
RG-11/U
RG-59/U
RG-214/U
Refer to Fig. 9-39. The beam width of this antenna pattern is approximately
30
38
45
60
A receiver-transmitter station used to increase the communications range of VHF, UHF, and microwave signals is called a(n)
Transceiver
Remitter
Repeater
Amplifier
SWR stands for:
Shorted Wave Radiation
Sine Wave Response
Shorted Wire Region
none of the above
TDR stands for:
Total Distance of Reflection
Time-Domain Reflectometer
Time-Domain Response
Transmission Delay Ratio
An example of an unbalanced line is:
a coaxial cable
300-ohm twin-lead TV cable
an open-wire-line cable
all of the above
When analyzing a transmission line, its inductance and capacitance are considered to be:
lumped
distributed
equal reactances
ideal elements
As frequency increases, the resistance of a wire:
increases
decreases
stays the same
changes periodically
The effect of frequency on the resistance of a wire is called:
I 2 R loss
the skin effect
the Ohmic effect
frequency effect
As frequency increases, the loss in a cable's dielectric:
increases
decreases
stays the same
there is no loss in a dielectric
The characteristic impedance of a cable depends on:
the resistance per foot of the wire used
the resistance per foot and the inductance per foot
the resistance per foot and the capacitance per foot
the inductance per foot and the capacitance per foot
For best matching, the load on a cable should be:
lower than Z 0
equal to Z 0
higher than Z 0
50 ohms
The characteristic impedance of a cable:
increases with length
increases with frequency
increases with voltage
none of the above
The velocity factor of a cable depends mostly on:
the wire resistance
the dielectric constant
the inductance per foot
all of the above
A positive voltage pulse sent down a transmission line terminated in a short-circuit:
would reflect as a positive pulse
would reflect as a negative pulse
would reflect as a positive pulse followed by a negative pulse
would not reflect at all
On a Smith Chart, you 'normalize' the impedance by:
assuming it to be zero
dividing it by 2π
multiplying it by 2π
dividing it by Z
The radius of the circle you draw on a Smith Chart represents:
the voltage
the current
the impedance
none of the above
The center of the Smith Chart always represents:
zero
one
characteristic impedance
none of the above
A TDR is commonly used to:
measure the characteristic impedance of a cable
find the position of a defect in a cable
replace a slotted-line
all of the above
A cable that lacks symmetry with respect to ground is called (a) .
Parallel lines are usually operated as (a) lines since both wires are symmetrical with respect to ground.
Normally, a transmission line is terminated with a load equal to its (a) impedance.
Twisted-pair cables are transmission lines for relatively (a) frequencies.
To analyze a transmission line, it is necessary to use (a) parameters instead of lumped ones.
The increase of a wire's resistance with frequency is called the (a) effect.
The increase of a wire's resistance with frequency is caused by the (a) field inside the wire.
Dielectrics become more (a) as the frequency increases.
The inductance and capacitance of a cable are given per unit (a) .
Characteristic impedance is sometimes called (a) impedance.
A cable that is terminated in its characteristic impedance is called a (a) line.
A pulse sent down a cable terminated in a short-circuit will reflect with the (a) polarity.
The apparently stationary pattern of waves on a mismatched cable is called a (a) wave.
SWR stands for (a) -wave ratio.
The ideal value for SWR is (a) .
Transmission line impedances can be found using a (a) chart.
Short transmission-line sections called (a) can be used as capacitors or inductors.
Any cable that radiates energy can also (a) energy.
A (a) -dB loss in a cable means only half the power sent reaches the load.
It is often best to measure SWR at the (a) end of a cable.
Besides heat from I2R, the power a cable can carry is limited by the (a) voltage of its dielectric.
To normalize an impedance on a Smith Chart, you divide it by (a) .
The (a) of a Smith Chart always represents the characteristic impedance.
A (a) wavelength transmission line can be used a transformer.
A slotted line is used to make measurements in the (a) domain.
Radio waves were first predicted mathematically by:
Armstrong
Hertz
Maxwell
Marconi
Radio waves were first demonstrated experimentally by:
Armstrong
Hertz
Maxwell
Marconi
The technology that made cell phones practical was:
the microprocessor chip
the miniature cell-site
high-power microwave transmitters
all of the above
Cell phones reduce much of the problems of mobile communications with:
high power levels
reuse of frequencies
high antennas
all of the above
Which of the following are electromagnetic:
radio waves
light
gamma waves
all of the above
The electric and magnetic fields of a radio wave are:
perpendicular to each other
perpendicular to the direction of travel
both a and b
none of the above
TEM stands for:
Transverse Electromagnetic
Transmitted Electromagnetic
True Electromagnetic
none of the above
In free space, radio waves travel at a speed of:
3 × 10^6 meters per second
300 × 10^6 meters per second
3 × 10^6 miles per second
300 × 10^6 miles per second
Which is a possible polarization for an electromagnetic wave:
vertical
horizontal
circular
all of the above
Which polarization can be reasonably well received by a circularly polarized antenna:
vertical
horizontal
circular
all of the above
The number of circular polarization modes (directions) is:
1
2
3
many
An antenna has 'gain' as compared to:
an isotropic radiator
a vertically polarized radiator
none of the above
EIRP stands for:
the E and I fields of the Radiated Power
the Effective Isotropic Radiated Power
the Effective Internal Reflected Power
the Electric-field Intensity of the Radiated Power
The 'attenuation of free space' is due to:
losses in the characteristic impedance of free space
losses due to absorption in the upper atmosphere
the decrease in energy per square meter due to expansion of the wavefront
the decrease in energy per square meter due to absorption of the wavefront
Ground waves are most effective:
below about 2 MHz
above about 20 MHz
at microwave frequencies
when using horizontally polarized waves
Radio waves would most strongly reflect off:
a flat insulating surface of the right size
a flat dielectric surface of the right size
a flat metallic surface of the right size
a flat body of water
Radio waves sometimes 'bend' around a corner because of:
reflection
refraction
diffusion
diffraction
Space waves are:
line-of-sight
reflected off the ionosphere
same as sky waves
radio waves used for satellite communications
Sky waves:
are line-of-sight
bounce off the ionosphere
are same as space waves
are radio waves used for satellite communications
Sky waves cannot be 'heard':
close to the transmitter
far from the transmitter
in the 'silent' zone
in the 'skip' zone
A 20-dB reduction in the strength of a radio wave due to reflection is called:
fading
diffraction
frequency diversity
spatial diversity
'Ghosts' on a TV screen are an example of:
fading
diffraction
multipath distortion
cancellation due to reflection
A 'repeater' is used to:
send a message multiple times over a channel
send a message over multiple channels at the same time
extend the range of a radio communications system
cancel the effects of fading
Cellular phone systems rely on:
high power
the radio horizon
repeaters
frequency reuse
Radio waves were mathematically predicted by (a) .
Radio waves were first demonstrated by (a) .
Radio waves are (a) electromagnetic waves.
The propagation speed of radio waves in free space is (a) m/sec.
Electromagnetic radiation can be thought of as a stream of particles called (a) .
Unlike sound or water waves, radio waves do not need a (a) to travel through.
The dielectric strength of clean dry air is about (a) volts per meter.
Waves from an (a) source radiate equally in all directions.
The wavefront of a point source would have the shape of a (a) .
At a far distance from the source, a radio wavefront looks like a flat (a) -wave.
The polarization of a radio wave is the direction of its (a) field.
The electric field of a radio wave is (a) to its magnetic field.
Both the electric and magnetic fields of a radio wave are (a) to its propagation direction.
With (a) polarization, the direction of a radio wave's electric field rotates as it travels through space.
An antenna is said to have (a) in a certain direction if it radiates more power in that direction than in other directions.
The watts per square meter of a radio wave (a) as the wave-front moves through space.
Reflection of plane-waves from a smooth surface is called (a) reflection.
(a) is the 'bending' of radio waves as they travel across the boundary between two different dielectrics.
The process of (a) makes radio waves appear to 'bend around a corner'.
(a) waves travel from transmitter to receiver in a 'line-of-sight' fashion.
(a) waves are vertically polarized radio waves that travel along the earth's surface.
(a) waves are radio waves that 'bounce off' the ionosphere due to refraction.
The (a) zone is a region where sky waves cannot be received.
'Ghosts' on a TV screen are an example of (a) distortion.
The 'fast fading' seen in mobile communications is caused by (a) waves interfering with direct waves.
Cell phones typically operate at a (a) power level.
The (a) of frequencies allows many cell-phone users to share a geographical area.
(a) is when a cell-site uses three directional antennas, each covering a third of the cell area, to reduce interference.
The use of (a) chips makes cell phones a practical technology.
A certain dielectric has permittivity of 6.3 ́ 10–10 F/m and the same permeability as free space. What is the characteristic impedance of that dielectric?
(a)
If a point source of radio waves transmits 1 watt, what is the power density 10,000 meters from the source?
(a)
What power must a point-source of radio waves transmit so that the power density at 3000 meters from the source is 1 mW/m2?
(a)
If a radio receiver needs 1 nW/m2 of power density to function, how far away from a 1-watt point source will it continue to work?
(a)
A line-of-sight radio link over flat terrain needs to use antenna towers 50 km apart. What, approximately, is the minimum height for the towers assuming all the towers are the same?
(a)
A mobile radio is being used at 1 GHz in an urban environment with lots of reflecting structures. If the car is traveling 36 km/hour, what is the expected time between fades?
(a)
The real part of an antenna's input impedance is due to:
the radiated signal
the reflected signal
the SWR
all of the above
A half-wave dipole is sometimes called:
a Marconi antenna
a Hertz antenna
a Yagi antenna
none of the above
The end-to-end length of a half-wave dipole antenna is actually:
one wavelength
one half-wavelength
slightly longer than a half-wavelength
slightly shorter than a half-wavelength
The radiation of energy from an antenna can be seen in the:
standing wave pattern around the antenna
SWR along the feed cable
radiation resistance of the antenna
I2R loss of the antenna
Measured on the ground, the field strength of a horizontally polarized half-wave dipole antenna is strongest:
in one direction
in two directions
in all directions
depends on the number of elements
The ability of an antenna to radiate more energy in one direction than in other directions is called:
directivity
selectivity
active antenna
resonance
The front-to-back ratio of a half-wave dipole antenna is:
0 dB
3 dB
10 dB
infinite
An antenna's beamwidth is measured:
from +90° to –90°
from front to back
between half-power points
between the minor side-lobes
ERP stands for:
Equivalent Radiation Pattern
Effective Radiation Pattern
Equivalent Radiated Power
Effective Radiated Power
'Ground Effects' refers to the effects on an antenna's radiation pattern caused by:
radio signals reflecting off the ground
buildings and other structures on the ground
fading
faulty connection of the feed cable ground
A 1-MHz monopole antenna must be:
mounted vertically
mounted horizontally
at least one half-wavelength long
at least one wavelength long
The typical antenna in an AM radio is a:
dipole
folded dipole
ferrite 'loop-stick'
none of the above
The polarization of plane waves received from a satellite is changed by:
gamma rays
Faraday Rotation
helical rotation
the distance traveled
A nonresonant antenna:
will not transmit
will not receive
will cause SWR on the feed cable
all of the above
At resonance, the input impedance to a lossless antenna should be:
resistive
inductive
capacitive
infinite
An antenna can be matched to a feed line using:
a shorted stub
a loading coil
an LC network
all of the above
As the length of a 'long-wire' antenna is increased:
the number of lobes increases
the number of nodes decreases
efficiency decreases
none of the above
Arrays can be:
phased
driven
parasitic
all of the above
An array with one driven element, a reflector, and one or more directors is called a:
Marconi
Yagi
Log-Periodic Dipole
stacked array
LPDA stands for:
Low-Power Dipole Array
Low-Power Directed Array
Log-Periodic Dipole Array
Log Power Dipole Array
The radiated beam from a parabolic 'dish' transmitting antenna is:
collimated
phased
dispersed
none of the above
The energy picked up by a parabolic antenna is concentrated at the:
center
edges
focus
horn
Antennas are often tested in:
an echo chamber
an anechoic chamber
a vacuum chamber
an RF reflective chamber
Field strength at a distance from an antenna is measured with:
a slotted line
a dipole
an EIRP meter
a field-strength meter
(undefined = 1, undefined = 4)
