Blake: MCQs in Microwave Devices

This is the Multiple Choice Questions in Chapter 17: Microwave Devices 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 microwave frequency range is considered to start at:

• a. 100 MHz
• b. 1 GHz
• c. 10 GHz
• d. 100 GHz

ANS: B

2. The UHF range is:

• a. below the microwave range
• b. inside the microwave range
• c. above the microwave range
• d. same as the microwave range

ANS: A

3. The dominant mode of a waveguide depends on:

• a. the shape of the waveguide
• b. the power level of the signal
• c. the point of signal injection
• d. none of the above

ANS: A

4. The dominant mode of a rectangular waveguide is:

• a. TE ₀₁
• b. TM ₀₁
• c. TE ₁₀
• d. TM₁₀

ANS: C

5. The dominant mode of a circular waveguide is:

• a. TE₀₁
• b. TM₀₁
• c. TE₁₁
• d. TM₁₁

ANS: C

6. Circular waveguides use TM₀₁ mode because:

• a. it is dominant
• b. of its circular symmetry
• c. it is the only mode possible
• d. it is more efficient

ANS: B

7. The characteristic impedance of a waveguide:

• a. is fixed
• b. depends on the frequency it carries
• c. depends on the longer dimension of its cross section
• d. both b and c

ANS: D

8. Power can be coupled into or out of a waveguide:

• a. with a magnetic field probe
• b. with an electric field probe
• c. through a hole in the waveguide
• d. all of the above

ANS: D

9. Directional couplers for waveguides are characterized by:

• a. their insertion loss
• b. their coupling specification
• c. their directivity
• d. all of the above

ANS: D

10. Striplines and microstrips are used to:

• a. couple sections of waveguide
• b. couple waveguides to antennas
• c. couple components on a circuit board
• d. none of the above

ANS: C

11. A resonant cavity is a type of:

• a. tuned circuit
• b. defect in a waveguide
• c. antenna
• d. none of the above

ANS: A

12. A TEE connector used with waveguides is:

• a. an H-plane TEE
• b. an E-plane TEE
• c. a "magic" TEE
• d. all of the above

ANS: D

13. TWT stands for:

• a. Transverse Wave Transmission
• b. Transverse-Wave Tube
• c. Traveling-Wave Tube
• d. Traveling-Wave Transmission

ANS: C

14. An "isolator" is a device that:

• a. isolates frequencies in a waveguide
• b. allows a signal to pass in one direction only
• c. separates signals among various ports
• d. prevents microwaves from leaking out of a waveguide

ANS: B

15. A "circulator" is a device that:

• a. rotates signal polarity in a waveguide
• b. allows a signal to pass in one direction only
• c. separates signals among various ports
• d. prevents microwaves from being "trapped" in a waveguide

ANS: C

16. GaAs stands for:

• a. gallium arsenide
• b. gallium assembly
• c. gallium astenite
• d. none of the above

ANS: A

17. IMPATT stands for:

• a. impact avalanche and transit time
• b. induced mobility at transmission time
• c. implied power at transmission terminal
• d. none of the above

ANS: A

18. YIG stands for:

• a. Yttrium-Iron-Gallium
• b. Yttrium-Iron-Germanium
• c. Yttrium-Iron-Garnet
• d. none of the above

ANS: C

19. A YIG can be tuned by applying:

• a. an electric field
• b. a magnetic field
• c. mechanical pressure
• d. an "exciter" signal

ANS: B

20. The device commonly used in microwave ovens is the:

• a. TWT
• b. klystron
• c. magnetron
• d. YIG

ANS: C

21. The device commonly used in satellite communications is the:

• a. TWT
• b. klystron
• c. magnetron
• d. YIG

ANS: A

22. The device commonly used in UHF transmitters is the:

• a. TWT
• b. klystron
• c. magnetron
• d. YIG

ANS: B

23. A microwave phased array is often made using:

• a. slots
• b. Yagis
• c. Fresnel lenses
• d. all of the above

ANS: A

24. RADAR stands for:

• a. radio ranging
• b. radio depth and ranging
• c. radio detection and ranging
• d. remote detection and ranging

ANS: C

25. RADAR uses:

• a. pulsed transmission
• b. continuous transmission
• c. the Doppler effect
• d. all of the above

ANS: D

26. The maximum effective range for pulsed radar:

• a. increases with increasing repetition rate
• b. decreases with increasing repetition rate
• c. decreases with increasing pulse period
• d. none of the above

ANS: B

27. The minimum effective range for pulsed radar:

• a. increases with increasing pulse duration
• b. decreases with increasing pulse duration
• c. is always a tenth of the maximum range
• d. none of the above

ANS: A

COMPLETION

1. ____________________ is the effect of a pulse "spreading out" as it travels through a waveguide.

ANS: Dispersion

2. The electric field is ____________________ along the walls of a rectangular waveguide.

ANS: zero

3. The waveguide mode with the lowest cutoff frequency is the ____________________ mode.

ANS: dominant

4. In TE10 mode, the ____________________ field peaks in the middle of the waveguide cross section.

ANS: electric

5. In TE20 mode, the electric field has ____________________ peaks in the waveguide cross section.

ANS: two

6. In a circular waveguide, ____________________ mode is used because of its circular symmetry.

ANS: TM01

7. A waveguide acts as a ____________________-pass filter.

ANS: high

8. In a waveguide, group velocity is always ____________________ than the speed of light.

ANS: slower

9. In a waveguide, phase velocity is always ____________________ than the speed of light.

ANS: faster

10. In a waveguide, impedance ____________________ as frequency increases.

ANS: decreases

11. A ____________________ TEE is a combination of E-plane and H-plane TEES.

ANS: hybrid

12. The Q of a resonant cavity is very ____________________ compared to lumped LC circuits.

ANS: high

13. A wavemeter is a resonant ____________________ with an adjustable plunger.

ANS: cavity

14. A Gunn device oscillates because of its negative ____________________.

ANS: resistance

15. Both magnetrons and TWTs are slow ____________________ tubes.

ANS: wave

16. Both klystrons and TWTs are ____________________-beam tubes.

ANS: linear

17. A ____________________ antenna is just a waveguide with a hole in it.

ANS: slot

18. A ____________________ antenna is a flat piece of copper on an insulating substrate with a ground plane on the other side.

ANS: patch

19. The radar cross section of a target is typically ____________________ than its actual size.

ANS: smaller

20. The frequency of the returned signal will be ____________________ than the transmitted signal if the target is moving toward the radar antenna.

ANS: higher

SHORT ANSWER

1. Calculate the TE₁₀ cutoff frequency for a rectangular waveguide if the longer dimension of its cross section is 5 cm.

ANS:

3 GHz

2. Calculate the group velocity in a waveguide carrying a signal that is twice its cutoff frequency.

ANS:

260 x 10⁶ meters per second

3. Calculate the phase velocity in a waveguide carrying a signal that is twice its cutoff frequency.

ANS:

346 x 10⁶ meters per second

4. Calculate the wavelength of a 2-GHz signal in a waveguide with a 1-GHz cutoff frequency.

ANS:

173 millimeters

5. Find the gain in dBi of a 10-GHz horn antenna with d_E = d_H= 60 mm.

ANS:

14.8

6. Find the maximum unambiguous range for a pulsed radar sending 10k pulses per second.

ANS:

15 km

7. Find the minimum unambiguous range for a pulsed radar sending 2-µsec duration pulses.

ANS:

300 meters

Complete List of MCQs in Electronic Communication Systems by Blake

Multiple Choice Questions in Electronic Communication Systems - Blake

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