 # Blake: MCQ in Antenna

(Last Updated On: January 10, 2018)

This is the Multiple Choice Questions in Chapter 16: Antenna from the book Electronic Communication Systems by Roy Blake . 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:

• 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:

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
• 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
• c. helical rotation
• d. the distance traveled

ANS: B

14. A nonresonant antenna:

• a. will not transmit
• 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
• 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.

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

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

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