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# Kennedy: MCQ in Waveguides, Resonators and Components

This is the Multiple Choice Questions in Chapter 10: Waveguides, Resonators and Components from the book Electronic Communication Systems by George Kennedy. 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.

1. When an electromagnetic waves are propagated in a waveguide

a. they travel along a broader walls of the guide

b. they are reflected from the walls but do not travel along them

c. they travel through the dielectric without touching the walls

d. they travel along all four walls of the waveguide

Solution:

2. Waveguides are used mainly for microwave signals because

a. they depend on straight-line propagation which applies to microwaves only

b. losses would be too heavy at lower frequencies

c. there are no generators powerful enough to excite them at lower frequencies

d. they would be too bulky at lower frequencies

Solution:

3. The wavelength of a wave in a waveguide

a. is greater than of free space

b. depends only on the waveguide dimensions and the free-space wavelength

c. is inversely proportional to the phase velocity

d. is directly proportional to the group velocity

Solution:

4. The main difference between the operation of transmission lines and waveguides is that

a. the latter are not distributed, like transmission lines

b. the former can use stubs and quarter-wave transformers, unlike the latter

c. transmission lines use the principal mode of propagation, and therefore do not suffer from low-frequency cut-off

d. terms such as impedance matching and standing-wave ratio cannot be applied to waveguides

Solution:

5. Compared with equivalent transmission lines, 3-GHz waveguides (indicate false statement)

a. are less lossy

b. can carry higher powers

c. are less bulky

d. have lower attenuation

Solution:

6. When a particular mode is excited in a waveguide, three appears an extra electric component, in the direction of propagation. The resulting mode is

a. transverse-electric

b. transverse-magnetic

c. longitudinal

d. transverse-electromagnetic

Solution:

7. When electromagnetic waves are reflected at an angle from a wall, their wavelength along the wall is

a. the same as in free space

b. the same as the wavelength perpendicular to the wall

c. shortened because of Doppler effect

d. greater than in the actual direction of propagation

Solution:

8. As a result of reflections from a plane conducting wall, electromagnetic waves acquire an apparent velocity greater than the velocity of light in space. This is called the

a. velocity of propagation

b. normal velocity

c. group velocity

d. phase velocity

Solution:

9. Indicate the false statement. When the free space wavelength of a signal equals the cut-off wavelength of the guide

a. the group velocity of the signal becomes zero

b. the phase velocity of the signal becomes infinite

c. the characteristic impedance of the guide becomes infinite

d. the wavelength within the waveguide becomes infinite

Solution:

10. A signal propagation in a waveguide has a full wave of electric intensity change between the two further walls, and no component of the electric field in the direction of propagation. The mode is

a. TE1,1

b. TE1,0

c. TM2,2

d. TE2,0

Solution:

11. The dominant mode of propagation is preferred with rectangular waveguides because (indicate false statement)

a. it leads to the smallest waveguide dimensions

b. the resulting impedance can be matched directly to coaxial lines

c. it is easier than the other modes

d. propagation of it without any spurious generation can be ensured

Solution:

12. A choke flange may be used to couple two waveguides

a. to help in the alignment of the waveguides

b. because it is simpler than any other join

c. to compensate for discontinuities at the join

d. to increase the bandwidth of the system

Solution:

13. In order to couple two generators to a waveguide system without coupling them to each other, on could not use a

a. rat-race

b. E-plane T

c. hybrid ring

d. magic T

Solution:

14. Which of the following waveguides tuning components is not easily adjustable?

a. Screw

b. Stub

c. Iris

d. Plunger

Solution:

15. A piston attenuator is a

a. vane attenuator

b. waveguide below cutoff

c. mode filter

d. flap attenuator

Solution:

16. Cylindrical cavity resonators are not used with klystrons because they have

a. a Q that is too low

b. a shape whose resonant frequency is too difficult to calculate

c. harmonically related resonant frequencies

d. too heavy losses

Solution:

17. A directional coupler with three or more holes is sometimes used in preference to the two-hole coupler

a. because it is more efficient

b. to increase coupling of the signal

c. to reduce spurious mode generation

d. to increase the bandwidth of the system

Solution:

18. A ferrite is

a. a nonconductive with magnetic properties

b. an intermetallic compound with particularly good conductivity

c. an insulator which heavily attenuates magnetic fields

d. a microwave semiconductor invented by Faraday

Solution:

19. Manganese ferrite may be used as a (indicate false answer)

a. circulator

b. isolator

c. garnet

d. phase shifter

Solution:

20. The maximum power that may be handled by a ferrite component is limited by the

a. Curie temperature

b. Saturation magnetization

c. line width

d. gyromagnetic resonance

Solution:

21. A PIN diode is

a. a metal semiconductor point-contact diode

b. a microwave mixer diode

c. often used as a microwave detector

d. suitable for use as a microwave switch

Solution:

22. A duplexer is used

a. to couple two different antennas to a transmitter without mutual interference

b. to allow the one antenna to be used for reception or retransmission without mutual interference

c. to prevent interference between two antennas when they are connected to a receiver

d. to increase the speed of the pulses in pulses in pulsed radar

Solution:

23. For some applications, circular waveguides may be preferred to rectangular ones because of

a. the smaller cross

b. lower attenuation

section needed at any frequency

c. freedom from spurious modes

d. rotation of polarization

Solution:

24. Indicate which of the following cannot be followed by the word โwaveguideโ:

a. Elliptical

b. Flexible

c. Coaxial

d. Ridged

Solution:

25. In order to reduce cross-sectional dimensions, the waveguide to use is

a. circular

b. ridged

c. rectangular

d. flexible

Solution:

26. For low attenuation, the best transmission medium is

a. flexible waveguide

b. ridged waveguide

c. rectangular waveguide

d. coaxial line

Solution:

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

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