# Blake: MCQ in Microwave Devices

(Last Updated On: January 6, 2020) 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

Solution:

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

Solution:

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

Solution:

4. The dominant mode of a rectangular waveguide is:

a. TE 01

b. TM 01

c. TE 10

d. TM 10

Solution:

5. The dominant mode of a circular waveguide is:

a. TE01

b. TM01

c. TE11

d. TM11

Solution:

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

Solution:

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

Solution:

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

Solution:

9. Directional couplers for waveguides are characterized by:

a. their insertion loss

b. their coupling specification

c. their directivity

d. all of the above

Solution:

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

Solution:

11. A resonant cavity is a type of:

a. tuned circuit

b. defect in a waveguide

c. antenna

d. none of the above

Solution:

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

Solution:

13. TWT stands for:

a. Transverse Wave Transmission

b. Transverse-Wave Tube

c. Traveling-Wave Tube

d. Traveling-Wave Transmission

Solution:

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

Solution:

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

Solution:

16. GaAs stands for:

a. gallium arsenide

b. gallium assembly

c. gallium astenite

d. none of the above

Solution:

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

Solution:

18. YIG stands for:

a. Yttrium-Iron-Gallium

b. Yttrium-Iron-Germanium

c. Yttrium-Iron-Garnet

d. none of the above

Solution:

19. A YIG can be tuned by applying:

a. an electric field

b. a magnetic field

c. mechanical pressure

d. an “exciter” signal

Solution:

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

a. TWT

b. klystron

c. magnetron

d. YIG

Solution:

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

a. TWT

b. klystron

c. magnetron

d. YIG

Solution:

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

a. TWT

b. klystron

c. magnetron

d. YIG

Solution:

23. A microwave phased array is often made using:

a. slots

b. Yagis

c. Fresnel lenses

d. all of the above

Solution:

d. remote detection and ranging

Solution:

a. pulsed transmission

b. continuous transmission

c. the Doppler effect

d. all of the above

Solution:

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

Solution:

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

Solution:

COMPLETION

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

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

15. Both magnetrons and TWTs are slow ____________________ tubes.

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Answer: 260 x 106 meters per second

Solution:

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

Answer: 346 x 106 meters per second

Solution:

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

Solution:

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

Solution:

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

Solution:

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

Solution:

### Complete List of MCQ in Electronic Communication Systems by Blake

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