Blake: MCQ in Antenna

(Last Updated On: January 10, 2018)
Blake: MCQs in Antenna

This is the Multiple Choice Questions in Chapter 16: Antenna from the book Electronic Communication Systems by Roy BlakeBlake: MCQ in Antenna. If you are looking for a reviewer in Communications Engineering this will definitely help. I can assure you that this will be a great help in reviewing the book in preparation for your Board Exam. Make sure to familiarize each and every questions to increase the chance of passing the ECE Board Exam.

Start Practice Exam Test Questions

Choose the letter of the best answer in each questions.

MULTIPLE CHOICE

1. The real part of an antenna’s input impedance is due to:

  • a. the radiated signal
  • b. the reflected signal
  • c. the SWR
  • d. all of the above

ANS: A

2. A half-wave dipole is sometimes called:

  • a. a Marconi antenna
  • b. a Hertz antenna
  • c. a Yagi antenna
  • d. none of the above

ANS: B

3. The end-to-end length of a half-wave dipole antenna is actually:

  • a. one wavelength
  • b. one half-wavelength
  • c. slightly longer than a half-wavelength
  • d. slightly shorter than a half-wavelength

ANS: D

4. The radiation of energy from an antenna can be seen in the:

  • a. standing wave pattern around the antenna
  • b. SWR along the feed cable
  • c. radiation resistance of the antenna
  • d. I2R loss of the antenna

ANS: C

5. Measured on the ground, the field strength of a horizontally polarized half-wave dipole antenna is

strongest:

  • a. in one direction
  • b. in two directions
  • c. in all directions
  • d. depends on the number of elements

ANS: B

6. The ability of an antenna to radiate more energy in one direction than in other directions is called:

  • a. directivity
  • b. selectivity
  • c. active antenna
  • d. resonance

ANS: A

7. The front-to-back ratio of a half-wave dipole antenna is:

  • a. 0 dB
  • b. 3 dB
  • c. 10 dB
  • d. infinite

ANS: A

8. An antenna’s beamwidth is measured:

  • a. from +90° to –90°
  • b. from front to back
  • c. between half-power points
  • d. between the minor side-lobes

ANS: C

9. ERP stands for:

  • a. Equivalent Radiation Pattern
  • b. Effective Radiation Pattern
  • c. Equivalent Radiated Power
  • d. Effective Radiated Power

ANS: D

10. "Ground Effects" refers to the effects on an antenna’s radiation pattern caused by:

  • a. radio signals reflecting off the ground
  • b. buildings and other structures on the ground
  • c. fading
  • d. faulty connection of the feed cable ground

ANS: A

11. A 1-MHz monopole antenna must be:

  • a. mounted vertically
  • b. mounted horizontally
  • c. at least one half-wavelength long
  • d. at least one wavelength long

ANS: A

12. The typical antenna in an AM radio is a:

  • a. dipole
  • b. folded dipole
  • c. ferrite "loop-stick"
  • d. none of the above

ANS: C

13. The polarization of plane waves received from a satellite is changed by:

  • a. gamma rays
  • b. Faraday Rotation
  • c. helical rotation
  • d. the distance traveled

ANS: B

14. A nonresonant antenna:

  • a. will not transmit
  • b. will not receive
  • c. will cause SWR on the feed cable
  • d. all of the above

ANS: C

15. At resonance, the input impedance to a lossless antenna should be:

  • a. resistive
  • b. inductive
  • c. capacitive
  • d. infinite

ANS: A

16. An antenna can be matched to a feed line using:

  • a. a shorted stub
  • b. a loading coil
  • c. an LC network
  • d. all of the above

ANS: D

17. As the length of a "long-wire" antenna is increased:

  • a. the number of lobes increases
  • b. the number of nodes decreases
  • c. efficiency decreases
  • d. none of the above

ANS: A

18. Arrays can be:

  • a. phased
  • b. driven
  • c. parasitic
  • d. all of the above

ANS: D

19. An array with one driven element, a reflector, and one or more directors is called a:

  • a. Marconi
  • b. Yagi
  • c. Log-Periodic Dipole
  • d. stacked array

ANS: B

20. LPDA stands for:

  • a. Low-Power Dipole Array
  • b. Low-Power Directed Array
  • c. Log-Periodic Dipole Array
  • d. Log Power Dipole Array

ANS: C

21. The radiated beam from a parabolic "dish" transmitting antenna is:

  • a. collimated
  • b. phased
  • c. dispersed
  • d. none of the above

ANS: A

22. The energy picked up by a parabolic antenna is concentrated at the:

  • a. center
  • b. edges
  • c. focus
  • d. horn

ANS: C

23. Antennas are often tested in:

  • a. an echo chamber
  • b. an anechoic chamber
  • c. a vacuum chamber
  • d. an RF reflective chamber

ANS: B

24. Field strength at a distance from an antenna is measured with:

  • a. a slotted line
  • b. a dipole
  • c. an EIRP meter
  • d. a field-strength meter

ANS: D

COMPLETION

1. An antenna is the interface between the transmission line and ____________________.

ANS: space

2. Hertz antenna is another name for a half-wave ____________________.

ANS: dipole

3. The length of a half-wave dipole is about ____________________ % of a half-wave in free space.

ANS: 95

4. The ____________________ resistance is the portion of an antenna’s input impedance due to transmitted radio waves leaving the antenna.

ANS: radiation

5. Input impedance at the center feed point of a resonant half-wave dipole is about ____________________ W.

ANS: 70

6. Input impedance at the center feed point of a resonant folded dipole is about ____________________ W.

ANS: 280 – 300

7. The vertical angle of radiation is called the angle of ____________________.

ANS: elevation

8. Antenna radiation patterns are typically drawn on graphs with ____________________ coordinates.

ANS: polar

9. As compared to a ____________________ source, a half-wave dipole has a gain of about 2 dBi.

ANS:

point

isotropic

10. Antenna gain measured in ____________________ is with reference to a half-wave dipole.

ANS: dBd

11. ____________________ is the same as the gain for a lossless antenna.

ANS: Directivity

12. The front-to-back ratio of a half-wave dipole is ____________________ dB.

ANS: 0

13. The ____________________ of a directional antenna is the angle between its half-power points.

ANS: beamwidth

14. ERP stands for ____________________ radiated power.

ANS: effective

15. ERP is the power input to the antenna multiplied by the antenna’s ____________________.

ANS: gain

16. A ____________________ is required to connect a coaxial cable to a center-fed dipole antenna.

ANS: balun

17. A horizontally mounted dipole will radiate waves with ____________________ polarization.

ANS: horizontal

18. A folded dipole has ____________________ bandwidth than a standard dipole.

ANS:

wider

greater

more

19. A monopole antenna is typically mounted in the ____________________ direction.

ANS: vertical

20. The length of a typical monopole antenna is ____________________ wavelength.

ANS:

one-quarter

1/4

21. A monopole antenna mounted high on a tower typically uses a ____________________ plane.

ANS: ground

22. A vertical antenna has an _________________________ radiation pattern for ground-based receivers.

ANS: omnidirectional

23. The number of driven elements in a Yagi antenna is typically ____________________.

ANS: one

24. The reflector on a Yagi antenna is called a ____________________ element.

ANS: parasitic

25. An LPDA is a ____________________ dipole array.

ANS: log-periodic

26. If an LPDA had five elements, the number of driven elements it had would be ____________________.

ANS: five

27. All the waves that hit the surface of a parabolic antenna merge at the ____________________.

ANS: focus

28. A ____________________ beam has all its individual rays parallel to each other.

ANS: collimated

29. A microwave ____________________ antenna is essentially an extension of a waveguide.

ANS: horn

30. An ____________________ chamber is often used to test microwave antennas.

ANS: anechoic

SHORT ANSWER

1. Calculate the physical length of a half-wave dipole for use at 300 MHz.

ANS:

475 millimeters

2. How much power will a 95% efficient antenna radiate if driven with 100 watts?

ANS:

95 watts

3. If an antenna has 10.14 dB of gain compared to a point source, how much gain does it have compared to a half-wave dipole?

ANS:

8 dB

4. What is the ERP of an antenna with 10 dBd of gain and driven by one watt?

ANS:

10 watts

5. A resonant antenna has an input impedance of 100 ohms and is driven by 100 watts. What is the RMS current in the antenna?

ANS:

1 ampere

6. A resonant antenna has an input impedance of 100 ohms and is driven by 100 watts. What is the RMS voltage at the feed-point of the antenna?

ANS:

100 volts

Complete List of MCQs in Electronic Communication Systems by Blake

Blake: MCQ in Antenna
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