ESAT RHM 2 - PART 1

Generate an image of a radio frequency (RF) antenna setup with a clear blue sky background, showcasing various antenna types and a radio tower, with technical diagrams in the foreground for educational context.

RF Antenna Theory Quiz

Test your knowledge on RF antennas with this comprehensive quiz designed for enthusiasts and professionals in the field of radio frequency communications. This quiz contains 122 questions covering various aspects of antennas, their design, functionality, and practical applications.

Whether you're a student, a teacher, or an industry professional, you'll find valuable insights that can enhance your understanding of RF engineering.

Comprehensive coverage of RF antennas
Multiple choice questions for effective assessment
Immediate feedback on your answers

122 Questions30 MinutesCreated by LearningWave254

Which of the following is not a reason why most half-wave antennas are mounted horizontally at low frequencies?

physical construction is easier

more cost-effective

mounting is easier

support is easier

The shape of the electromagnetic energy radiated from or received by an antenna is called the

signal shape

electromagnetic pattern

radiation pattern

antenna pattern

Antennas that transmit an equal amount of energy in the horizontal direction are called

Bi-directional

unidirectional

Omnidirectional

unilateral

The ability of an antenna to send or receive signals over a narrow horizontal directional range is referred to as

Focal factor

permittivity

directivity

horizontal range

A basic antenna connected to a transmission line plus one or more additional conductors that are not connected to the transmission line form a

parasitic array

bi-directional array

half-wave dipole

counterpoise

To obtain efficient power transmission from a transmitter to an antenna requires:

High load impedance

Low ohmic resistance

Matching of impedance

Inductive impedance

To obtain efficient transfer of power from a transmitter to an antenna, it is important that there is a:

high load impedance

Matching of impedance

Proper method of balance

low ohmic resistance

If an antenna is correctly matched to a transmitter, the length of transmission line:

must be a full wavelength long

Must be an odd number of quarter-wave

Must be an even number of half-waves

will have no effect on the matching

The reason that an RF transmission line should be matched at the transmitter end is to:

ensure that the radiated signal has the intended polarization

transfer the maximum amount of power to the antenna

Prevent frequency drift

Overcome fading of the transmitted signal

If the center impedance of a folded dipole is approximately 300 ohms, and you are using RG8U (50 ohms) coaxial lines, what is the ratio required to have the line and the antenna matched?

2:1

4:1

10:1

6:1

Atmospheric________of RF energy with no reflection or refraction that adversely affects long distance communications. This does not allow any reflection or refraction.

Absorption

Attenuation

Diffraction

None of the choices

The portion of a cycle measured from a reference line to a maximum value above (or to a maximum value below) the line.

phase

Frequency

Amplitude

Wavelength

The angle between the reflected wave and the normal.

angle of reflection

critical angle

acceptance angle

elevation angle

The unit used to define the wavelength of light waves.

Meter

Angstrom

Millimeter

Mil

A conductor or set of conductors used either to radiate rf energy into space or to collect rf energy from space.

Reflector

radiator

coaxial line

Antenna

Find the characteristics impedance of polyethylene, which has a dielectric constant of 2.3.

164 Ω

249 Ω

867 Ω

572 Ω

The dielectric strength of air is about 3 MV/m, Arcing is likely to take place at field strengths greater than that. What is the maximum power density of an electromagnetic wave in air?

23.9GW/m^2

11.9GW/m^2

A power of 100 W is supplied to an isotropic radiator. What is the power density at a point 10 km away?

79.6 nW/m^2

0.1 nW/m^2

32.2 nW/m^2

None of the above

A transmitter has a power output of 150 W at a carrier frequency of 325 MHz. It is connected to an antenna with a gain of 12 dBi. The receiving antenna is 10 km away and has a gain of 5 dBi. Calculate the power delivered to the receiver, assuming free-space propagation. Assume also that there are no losses or mismatches in the system.

-21.43dBW

-65.21dBW

-63.88dBW

-86.796 dBW

The change in the propagation constant for different waves is called

diffraction

constructive interference

Dispersion

Destructive interference

The change in the propagation constant for different wavelengths is called

Chromatic dispersion

Modal interference

Modal dispersion

Both chromatic and modal dispersion

Modes traveling in an optical fiber are said to be ________.

parallel

transverse

Parallel or transverse

In phase

The electric field is perpendicular to the direction of propagation and the magnetic field is in the direction of propagation.

TE and TM mode

None of the choices

An antenna made up of a driven element and one or more parasitic elements is generally referred to as a

Hertz antenna

Marconi antenna

Collinear antenna

Yagi antenna

Which antennas usually consist of two or more half-wave dipoles mounted end to end?

Hertz

Marconi

Collinear

Yagi

A stacked collinear antenna consisting of half-wave dipoles spaced from one another by one-half wavelengths is the

Broadside array

End-fire array

Wide-bandwidth array

Parasitic array

When the characteristic impedance of the transmission line matches the output impedance of the transmitter and the impedance of the antenna itself,

the SWR will be 10:1

the SWR will be 1:10

minimum power transfer will take place

Maximum power transfer will take place

What does horizontal wave polarization mean?

The electric and magnetic lines of force of a radio wave are perpendicular to the earth's surface

The electric lines of force of a radio wave are perpendicular to the earth's surface

The electric lines of force of a radio wave are parallel to the earth's surface

The magnetic lines of force of a radio wave are parallel to the earth's surface

What does vertical wave polarization mean?

The magnetic lines of force of a radio wave are perpendicular to the earth's surface

The electric lines of force of a radio wave are perpendicular to the earth's surface

What electromagnetic wave polarization does a Yagi antenna have when its elements are parallel to the earth's surface?

Helical

Horizontal

Vertical

Circular

What electromagnetic wave polarization does a half-wavelength antenna have when it is perpendicular to the earth's surface?

Circular

Horizontal

Parabolical

Vertical

Polarization of an antenna is determined by:

the height of the antenna

The electric field

the type of antenna

The magnetic field

A one-quarter wavelength of coaxial or balanced transmission line of a specific impedance connected between a load and a source in order to match impedances is

A balun

An autotransformer

a Q section

Dummy load

The microstrip lines shown in the circuit are used for

low-noise amplification

Decoupling to prevent feedback

impedance matching and tuning

signal coupling

Small wire loop inductors and capacitors are used to provide

low-noise amplification

decoupling to prevent feedback

signal coupling

Hollow metal conducting pipes designed to carry and constrain the electromagnetic waves of a microwave signal are

Wavetraps

Waveguides

Traveling wave tubes

Microwave tubes

An array that radiates in opposite directions along the line of maximum radiation.

bidirectional array

Directional array

Connecting the center of an antenna to a transmission line, which is then connected to the final (output) stage of the transmitter.

Feeding

Center feed method

End feed method

Output feed method

A type of transmission line that contains two concentric conductors.

Balance line

Coaxial line

Twin lead

Ladder

An array system that uses the characteristics of more than one array.

Mixed array

Single array

Multi array

combination array

A wave produced by combining two or more pure tones at the same time.

multi wave

simple wave

complex wave

Square wave

A transmitter has a power output of 10 W at a carrier frequency of 250 MHz. It is connected by 10 m of a transmission line having a loss of 3 dB/100 m to an antenna with a gain of 6 dBi. The receiving antenna is 20 km away and has a gain of 4 dBi. There is negligible loss in the receiver feedline, but the receiver is mismatched: the antenna and line are designed for a 50 Ω impedance, but the receiver input is 75 Ω. Calculate the power delivered to the receiver, assuming free-space propagation.

-65.21 dBW

-63.88 dBW

-78.43 dBW

-86.796 dBW

A radio wave moves from air (ϵr= 1) to glass (ϵr=7.8). Its angle of incidence is 30°. What is the angle of refraction?

10.3°

22.4°

19.3°

32.1°

The critical frequency at a particular time 11.6 MHz. What is the MUF for a transmitting station if the required angle of incidence for propagation to a desired destination if 70°?

31.7 MHz

32.6 MHz

97.1 MHz

33.9 MHz

A taxi company uses a central dispatcher, with an antenna at the top of a 15 m tower, to communicate with taxicabs. The taxi antennas are on the roofs of the cars, approximately 1.5 m above the ground. Calculate the maximum communication distance between the dispatcher and a taxi.

20 km

21 km

22 km

23 km

Determine the ghost width on a TV screen 15 in, wide when a reflected wave results from an object 1/2 mi “behind” a receiver.

1.51 in

2.11 in

3.22 in

4.97 in

The magnetic field is perpendicular to the direction of propagation.

TE and TM mode

None of the choices

_______ penetrate the cladding only slightly and the electric and magnetic fields are concentrated near of the center fiber.

high-order modes

Low-order modes

Both low-order and high-order modes

None of these choices

This penetrate further into the cladding material and the electrical and magnetic fields are distributed more toward the outer edges of the fiber.

low-order modes

high-order modes

Leaky modes:

multiply power as they propagate along the fiber

Gain power as they propagate along the fiber

lose power as they propagate along the fiber

divide power as they propagate along the fiber

It determines how many modes a fiber can support.

V index

Propagation mode

Critical frequency

Normalized frequency

53. Part of an antenna array.

Bay

. shore

Coast

Bank

54. The opposite of resistance in transmission lines. The minute amount of resistance that is present in the insulator of a transmission line.

Impedance

Conductance

Admittance

Reactance

55. The I^2R loss in a conductor caused by the current flow through the resistance of the conductor.

A. Copper loss

B. Dielectric loss

C. Radiation loss

D. Induction loss

56. A network of wire that is connected to a quarter-wave antenna at one end and provides the equivalent of an additional 1/4 wavelength.

Coaxial line

Ground screen

Counterpoise

top loading

57. The peak of the positive alternation (maximum value above the line) of a wave.

A. trough

B. summit

C. zenith

D. crest

58. For an isotropic antenna radiating 100 W of power, determine power density 1000 m and 2000 m from the source.

A. 7.96 µW/m^2 and 15.92 µW/m^2

C. 100 µW/m^2 and 200 µW/m^2

D. 100 µW/m^2 and 25 µW/m^2

59. A line-of-sight radio link operating at a frequency of 6 GHz has a separation of 40 km between antennas. An obstacle in the path is located 10 km from the transmitting antenna. By how much must the beam clear the obstacle?

11.6 m

32.1 m

29.4 m

16.9 m

60. Find the cutoff frequency for the TE10 mode in an air-dielectric waveguide with an inside cross section of 2 cm by 4 cm. Over what frequency range is the dominant mode the only one that will propagate?

A. 7.5 x 10^9 Hz; 3.75 GHz to 7.5 GHz

B. 3.75 × 10^9 Hz; 3.75 GHz to 7.5 GHz

C. 5 x 10^9 Hz; 1.875 GHz to 15 GHz

D. None of the above

61. Find the group velocity and phase velocity for the waveguide with TE10 mode with an inside cross section of 2 cm by 4 cm, at a frequency of 5 GHz.

A. 454 × 10^6 m/s; 1.98 × 10^8 m/s

B. 402 x 10^6 m/s; 2.23 x 10^8 m/s

C. 318 x 10^6 m/s; 2.82 x 10^8 m/s

D. 198 × 10^6 m/s; 4.54 × 10^8 m/s

62. A waveguide has a cutoff frequency for the dominant mode of 10 GHz. Two signals with frequencies of 12 and 17 GHz propagate down a 50 m length of the guide. Calculate the group velocity for each and the difference in arrival time for the two.

A. 242.6×10^6 m/s; 165.8×10^6 m/s; 95.5 ns

B. 165.8×10^6 m/s; 242.6×10^6 m/s; 95.5 ns

C. 112x10^6 m/s; 233x10^6 m/s; 32.2 ns

D. None of the above

63. The core size of single mode fibers is typically around

A. 10 to 100 mm

B. 8 to 10 cm

C. 10 to 100 um

D. 8 to 10 um

64. Single mode fibers are capable of transferring higher amounts of data due to _____?

A. Low fiber dispersion

B. Bigger core diameter

C. High fiber dispersion

D. Smaller cladding diameter

65. The number of modes propagated depends on ________ in multimode fibers.

A. Core size

B. Numerical aperture

C. Both core size and numerical aperture

D. None of the choices

66. What happens as the number of mode increases in multimode fibers?

A. The effect of modal dispersion decreases

B. The effect of modal dispersion increases

C. The index profile changes

D. The critical angle increases

67. In fiber, attenuation is mainly a result of ______.

A. scattering

B. Bending losses

C. Light absorption

D. All of the choices

68. A microwave component which is used to interconnect two sections of waveguide is the

A. T section

B. Curved section

C. Choke joint

D. Tapered wedge

69. A waveguide like device that acts as a high-Q parallel resonant circuit is a

A. microstrip

B. klystron

C. horn

D. Cavity resonator

70. A three-port microwave device used for coupling energy in only one direction around a closed loop is a

A. circulator

B. joint

C. terminator

D. Cavity resonator

71. Which of the following diodes is not typically used in the microwave region?

A. point-contact

B. standard PN

C. Schottky

D. Hot carrier

72. Which of the following diodes does not oscillate due to negative-resistance characteristics?

A. tunnel

B. SCR

C. Gunn

73. Adding a series inductance to an antenna would:

A. Increase the resonant frequency

B. Have little effect

C. Decrease the resonant frequency

D. Have no change on the resonant frequency

74. What is a parasitic beam antenna?

A. An antenna where the driven element obtains its radio energy by induction or radiation from director elements

B. An antenna where all elements are driven by direct connection to the feed line

C. An antenna where some elements obtain their radio energy by induction or radiation from a driven element

D. An antenna where wave traps are used to magnetically couple the elements

75. How can the bandwidth of a parasitic beam antenna be increased?

A. Use traps on the elements

B. Use larger diameter elements

C. Use tapered-diameter elements

D. Use closer element spacing

76. If a slightly shorter parasitic element is placed 0.1 wavelength away from an HF dipole antenna, what effect will this have on the antenna's radiation pattern?

A. A major lobe will develop in the horizontal plane, parallel to the two elements

B. A major lobe will develop in the horizontal plane, toward the parasitic element

C. A major lobe will develop in the vertical plane, away from the ground

D. The radiation pattern will not be affected

77. If a slightly longer parasitic elementis placed 0.1 wavelength away from an HF dipole antenna, what effect will this have on the antenna's radiation pattern?

A. A major lobe will develop in the horizontal plane, parallel to the two elements

B. A major lobe will develop in the vertical plane, away from the ground

C. A major lobe will develop in the horizontal plane, away from the parasitic element, toward the dipole

D. The radiation pattern will not be affected

78. The maximum frequency at which a radio wave can be transmitted vertically and still be refracted back to earth.

A. OWF

B. MUF

C. fc

D. fr

79. The ratio of maximum to minimum current along a transmission line.

A. VSWR

B. SWR

C. ISWR

D. Γ

80. Reduction of energy by absorption.

A. damping

B. Flywheel effect

C. attenuation

D. All of the choices

81. The device that responds to a wave or disturbance.

A. detector

B. diffusion

C. directional

D. Dielectric loss

82. The losses resulting from the heating effect on the dielectric material between conductors.

A. Copper loss

B. Dielectric loss

C. Radiation loss

D. Induction loss

83. Find the characteristics impedance and At what frequency will it oscillate in the transmit-time mode?

A. 360 Ω; 7.11 cm

B. 570 Ω; 9.08 cm

C. 300 Ω;

D. None of the above

84. A Gunn device has a thickness of 7 µm. At what frequency will it oscillate in the transmit-time mode?

28.6 GHz

21.45 GHz

14.3 GHz

None of the above

85. Calculate the power gain and bandwidth of a microwave dish antenna with a 3m mouth diameter when used at 10 GHz.

A. 101.5 dB; 3.2 deg

B. 47.8 dB; 0.7 deg

C. 32.0 dB; 1.1 deg

D. 60.26 dB; 0.01 deg

86. For a rectangular waveguide with a wall separation of 3 cm and a desired frequency of operation of 6 GHz, determine the cutoff wavelength.

A. 6 cm

B. 8 cm

C. 10 cm

D. 3 cm

87. A radar transmitter has a power of 10 kW and operates at a frequency of 9.5 GHz. Its signal reflects from a target 15 km away with a radar cross section of 10.2m^2. The gain of the antenna is 20 dBi. Calculate the received signal power.

A. 22.1 fW

B. 11.2 fW

C. 10.1 fW

D. 9.76 fW

88. It is the loss of optical power as light travels along the fiber.

A. Absorption

B. Dispersion

C. Attenuation

D. Scattering

89. The ratio of optical input power to the optical output power.

A. Absorption

B. Dispersion

C. Attenuation

D. Scattering

90. The portion of attenuation resulting from the conversion of optical power into another energy form, such as heat.

A. Absorption

B. Dispersion

C. Attenuation

D. Scattering

91. Determine the factor/s that causes absorption in optical fiber.

A. The extrinsic (presence of impurities) fiber-material properties

B. The intrinsic or basic fiber-material properties

C. Imperfections in the atomic structure of the fiber material

D. All of the choices

92. Caused by basic fiber-material properties.

A. Extrinsic absorption

B. Total internal reflection

C. Bending loss

D. Intrinsic absorption

93. A thin piece of N-type gallium arsenide or indium phosphide semiconductor which forms a special resistor when voltage is applied to it is the

A. Tunnel diode

B. PIN diode

C. Gunn diode

D. Varactor diode

94. A microwave vacuum tube using cavity resonators to produce velocity modulation of an electron beam which produces amplification is

A. A klystron

B. magnetron

C. A cathode-ray tube

D. traveling-wave tube

95. The original signal being transmitted from the earth station to the satellite is called the

A. transponder

B. originator

C. uplink

D. downlink

96. The transmitter-receiver combination in the satellite is known as a

A. transponder

B. transceiver

C. Telephonic unit

D. repeater

97. Most communication satellites operate in the

A. high-frequency spectrum

B. VHF spectrum

C. UHF spectrum

D. Microwave frequency spectrum

98. If an antenna is made longer, what happens to its resonant frequency?

A. It decreases

B. It increases

C. It stays the same

D. It disappears

99. If an antenna is made shorter, what happens to its resonant frequency?

A. It stays the same

B. It increases

C. It disappears

D. It decreases

100. The wavelength for a frequency of 25 MHz

A. 15 meters (49.2 ft)

B. 4 meters (13.1 ft)

C. 12 meters (39.4 ft)

D. 32 meters (105 ft)

100. The wavelength for a frequency of 25 MHz is:

A. 15 meters (49.2 ft)

B. 4 meters (13.1 ft)

C. 12 meters (39.4 ft)

D. 32 meters (105 ft)

99. If an antenna is made shorter, what happens to its resonant frequency?

A. It stays the same

B. It increases

C. It disappears

D. It decreases

{"name":"ESAT RHM 2 - PART 1", "url":"https://www.quiz-maker.com/QPREVIEW","txt":"Test your knowledge on RF antennas with this comprehensive quiz designed for enthusiasts and professionals in the field of radio frequency communications. This quiz contains 122 questions covering various aspects of antennas, their design, functionality, and practical applications.Whether you're a student, a teacher, or an industry professional, you'll find valuable insights that can enhance your understanding of RF engineering.Comprehensive coverage of RF antennasMultiple choice questions for effective assessmentImmediate feedback on your answers","img":"https:/images/course4.png"}