Antennas: A Comprehensive Guide for Electrical Engineering Students

Question 1

What is a primary advantage of using a Yagi-Uda antenna instead of a half-wave dipole antenna?

Accepted Answer

Increased gain

Answer

Reduced power handling

Answer

Expanded bandwidth

Answer

Lower cost

Question 2

Which type of antenna typically exhibits the highest gain?

Accepted Answer

Yagi-Uda antenna with 10 elements

Answer

Half-wave dipole antenna

Answer

Quarter-wave monopole antenna

Answer

Isotropic antenna

Question 3

Which of the following is NOT a type of antenna polarization?

Accepted Answer

Isotropic

Answer

Linear

Answer

Circular

Answer

Elliptical

Question 4

Which type of antenna has a radiation pattern that is omni-directional in the horizontal plane?

Accepted Answer

Half-wave dipole

Answer

Quarter-wave monopole

Answer

Yagi-Uda

Answer

Horn antenna

Question 5

What is the primary purpose of a balun in an antenna system?

Accepted Answer

To convert between balanced and unbalanced transmission lines

Answer

To match impedance between the antenna and the transmission line

Answer

To provide isolation between the antenna and the receiver

Answer

To suppress common-mode currents on the transmission line

Question 6

How does ground reflection impact the radiation pattern of a vertical monopole antenna?

Accepted Answer

It can create a null in the radiation pattern at certain angles

Answer

It can increase the gain of the antenna in the vertical direction

Answer

It can make the radiation pattern more omnidirectional

Answer

It has no effect on the radiation pattern

Question 7

Which type of antenna is commonly used in cell phone base stations?

Accepted Answer

Cell phone base stations

Answer

Satellite communications

Answer

Wi-Fi routers

Answer

Television broadcasting

Question 8

The length of a half-wave dipole antenna is:

Accepted Answer

λ/2

Answer

λ/4

Answer

λ

Answer

2λ

Question 9

Which type of antenna is widely used in mobile devices for communication?

Accepted Answer

Quarter-wave monopole antenna

Answer

Yagi-Uda antenna

Answer

Half-wave dipole antenna

Answer

Parabolic antenna

Question 10

The gain of an antenna quantifies its ability to:

Accepted Answer

Focus electromagnetic energy in a specific direction

Answer

Transmit power

Answer

Receive power

Answer

Increase signal bandwidth

Question 11

Which polarization type corresponds to electromagnetic waves that oscillate horizontally?

Accepted Answer

Linear horizontal

Answer

Linear vertical

Answer

Circular right-hand

Answer

Circular left-hand

Question 12

A Yagi-Uda antenna typically comprises:

Accepted Answer

A dipole element and several directors

Answer

A single dipole element

Answer

A dipole element and several reflectors

Answer

A parabolic reflector and a feed horn

Question 13

Which of the following is NOT an advantage of antenna arrays?

Accepted Answer

Enhanced frequency response

Answer

Increased directivity

Answer

Reduced side lobes

Answer

Improved signal-to-noise ratio

Question 14

The primary reason for impedance matching between an antenna and a transmission line is:

Accepted Answer

To maximize power transfer

Answer

To minimize signal reflections

Answer

To improve antenna gain

Answer

To reduce noise

Question 15

Which of the following parameters is used to quantify the ability of an antenna to focus its radiated power in a specific direction?

Accepted Answer

Gain

Answer

Beamwidth

Answer

Polarization

Answer

Effective area

Question 16

What is the function of a balun in an antenna system?

Accepted Answer

To convert balanced to unbalanced signals

Answer

To increase the antenna's bandwidth

Answer

To reduce the antenna's impedance

Answer

To improve the antenna's gain

Question 17

Which type of polarization is exhibited by a vertically oriented half-wave dipole antenna?

Accepted Answer

Linear vertical

Answer

Linear horizontal

Answer

Circular right-hand

Answer

Circular left-hand

Question 18

Which of the following antennas is typically used for high-frequency point-to-point communication links?

Accepted Answer

Parabolic dish

Answer

Microstrip patch

Answer

Yagi-Uda

Answer

Log-periodic

Question 19

Antenna impedance matching is crucial for optimizing its performance. Which parameter does it primarily affect?

Accepted Answer

Efficiency and bandwidth

Answer

Power handling capacity

Answer

Radiation pattern

Answer

Polarization

Question 20

What defines the orientation of the electromagnetic field radiated by an antenna?

Accepted Answer

Antenna polarization.

Answer

Antenna gain.

Answer

Antenna bandwidth.

Question 21

What is the radiation pattern of a half-wave dipole antenna?

Accepted Answer

Figure-eight shaped

Answer

Isotropic

Answer

Cardioid

Answer

Donut-shaped

Question 22

Which type of antenna is commonly used for mobile devices?

Accepted Answer

Quarter-wave monopole antenna

Answer

Yagi-Uda antenna

Answer

Parabolic reflector antenna

Answer

Horn antenna

Question 23

What is the purpose of a balun in an antenna system?

Accepted Answer

To match the impedance of the antenna to the transmission line.

Answer

To prevent standing waves on the transmission line.

Answer

To isolate the antenna from the ground.

Answer

To increase the gain of the antenna.

Question 24

Which of the following is an advantage of using a Yagi-Uda antenna?

Accepted Answer

High gain and narrow beamwidth

Answer

Lightweight and low cost

Answer

Isotropic radiation pattern

Answer

High efficiency at all frequencies

Question 25

What is the primary application of a horn antenna?

Accepted Answer

Radar systems

Answer

Satellite communications

Answer

Mobile devices

Answer

Medical imaging

Question 26

Explain how antenna arrays enhance signal directivity and gain compared to single antennas, discussing the concepts of array factor and beamforming.

Accepted Answer

Antenna arrays improve directivity by creating a more focused signal beam, reducing energy dissipation in undesired directions.

Answer

Antenna arrays enhance gain by increasing the physical size of the overall antenna structure.

Answer

Beamforming is a technique that cannot be applied to antenna arrays.

Question 27

What is the characteristic impedance of a standard half-wave dipole antenna?

Accepted Answer

73 ohms

Answer

100 ohms

Answer

50 ohms

Answer

300 ohms

Question 28

Which of the following is a measure of the directionality of an antenna?

Accepted Answer

Gain

Answer

Efficiency

Answer

Bandwidth

Answer

Polarization

Question 29

What is an advantage of using a Yagi-Uda antenna over a half-wave dipole antenna?

Accepted Answer

Higher gain

Answer

Lower cost

Answer

Wider bandwidth

Answer

Reduced size

Question 30

What is the purpose of a balun in an antenna system?

Accepted Answer

To match the impedance between the antenna and the transmission line

Answer

To reduce the antenna's bandwidth

Answer

To increase the antenna's power

Question 31

What is the difference between an isotropic and an anisotropic antenna?

Accepted Answer

Isotropic antennas radiate power equally in all directions, while anisotropic antennas do not.

Answer

Anisotropic antennas are more commonly used than isotropic antennas.

Answer

Isotropic antennas have higher gain than anisotropic antennas.

Question 32

Which type of antenna is often used for mobile communications?

Accepted Answer

Monopole antenna

Answer

Phased array antenna

Answer

Parabolic dish antenna

Answer

Horn antenna

Question 33

What is the primary function of a ground plane in an antenna system?

Accepted Answer

To provide a reference point for the antenna's electrical currents

Answer

To increase the antenna's power

Answer

To reduce the antenna's bandwidth

Question 34

What is the advantage of using a Yagi-Uda antenna?

Accepted Answer

It can focus the electromagnetic energy in a specific direction

Answer

It can suppress noise

Answer

It can reduce the bandwidth of operation

Answer

It can match the impedance between antenna and transmission line

Question 35

Which of the following does NOT affect the gain of an antenna?

Accepted Answer

Antenna location

Answer

Antenna efficiency

Answer

Operating frequency

Answer

Antenna size

Question 36

What is the relationship between the wavelength and the length of a half-wave dipole antenna?

Accepted Answer

λ/2

Answer

λ

Answer

3λ/2

Answer

2λ

Question 37

Which of the following is a limitation of the reciprocity theorem in antenna theory?

Accepted Answer

It is only applicable to lossless antennas

Answer

It is only applicable to antennas at low frequencies

Answer

It is only applicable to antennas with a single terminal

Answer

It is only applicable to antennas in a uniform medium

Question 38

What is the main purpose of a balun in antenna systems?

Accepted Answer

To match the impedance between balanced and unbalanced transmission lines

Answer

To reduce noise

Answer

To increase bandwidth

Answer

To improve the radiation pattern of the antenna

Question 39

What is the key advantage of using a smart antenna?

Accepted Answer

It can dynamically adjust its beamforming to optimize signal reception

Answer

It has a higher gain

Answer

It is smaller in size

Answer

It is less expensive to manufacture

Question 40

Which of the following is a fundamental characteristic of an antenna?

Accepted Answer

Radiation pattern

Answer

Voltage

Answer

Resistance

Answer

Current

Question 41

What is the primary difference between an isotropic antenna and a directional antenna?

Accepted Answer

Directivity

Answer

Efficiency

Answer

Polarization

Answer

Bandwidth

Question 42

Which of the following antennas is typically used for broadcasting radio signals over long distances?

Accepted Answer

Yagi-Uda antenna

Answer

Patch antenna

Answer

Half-wave dipole antenna

Answer

Monopole antenna

Question 43

What is the function of a balun in an antenna system?

Accepted Answer

To match impedances

Answer

To increase the antenna bandwidth

Answer

To isolate the antenna from the feed line

Answer

To reduce noise

Question 44

Which parameter is used to quantify the amount of power radiated by an antenna relative to the power input?

Accepted Answer

Radiation efficiency

Answer

Voltage efficiency

Answer

Power efficiency

Question 45

What is the purpose of an antenna ground plane?

Accepted Answer

To provide a reference plane for antenna currents

Answer

To reduce antenna losses

Answer

To improve the antenna's radiation pattern

Answer

To increase the antenna's bandwidth

Question 46

Which of the following is NOT a characteristic of an antenna?

Accepted Answer

Frequency of operation

Answer

Impedance

Answer

Radiation pattern

Answer

Gain

Question 47

A half-wave dipole antenna has a length of approximately:

Accepted Answer

λ/2

Answer

λ/4

Answer

2λ

Answer

λ

Question 48

A quarter-wave monopole antenna is typically used in conjunction with:

Accepted Answer

A ground plane

Answer

A reflector

Answer

A director

Answer

Another monopole antenna

Question 49

The radiation pattern of an antenna represents:

Accepted Answer

The spatial distribution of radiated power

Answer

The impedance of the antenna

Answer

The frequency response of the antenna

Question 50

Which of the following antennas is known for its high gain and directional characteristics?

Accepted Answer

Yagi-Uda antenna

Answer

Quarter-wave monopole antenna

Answer

Half-wave dipole antenna

Question 51

The gain of an antenna is defined as:

Accepted Answer

The ratio of power density in the desired direction to the power density of an isotropic antenna

Answer

The efficiency of the antenna

Answer

The total power radiated by the antenna

Question 52

The bandwidth of an antenna refers to:

Accepted Answer

The range of frequencies over which the antenna operates effectively

Answer

The maximum power that the antenna can handle

Answer

The efficiency of the antenna

Question 53

A resonant antenna is designed to:

Accepted Answer

Operate efficiently at a specific frequency

Answer

Minimize the impedance mismatch

Answer

Reduce the size of the antenna

Answer

Maximize the gain of the antenna

Question 54

Which of the following factors does NOT significantly affect the impedance of an antenna?

Accepted Answer

The color of the antenna

Answer

The length of the antenna

Answer

The presence of nearby objects

Answer

The frequency of operation

Question 55

A directional antenna is used to:

Accepted Answer

Concentrate radiated power in a specific direction

Answer

Increase the bandwidth of the antenna

Answer

Reduce the size of the antenna

Answer

Radiate power equally in all directions