 # Blake: MCQ in Microwave Devices

(Last Updated On: January 10, 2018)

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

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

ANS: C

• 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

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 dE = dH= 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

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