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# MCQ in Microwave Communications Part 10 | ECE Board Exam

This is the Multiples Choice Questions Part 10 of the Series in Microwave Communications as one of the Communications Engineering topic. In Preparation for the ECE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including but not limited to past Board Examination Questions in Electronic System and Technologies, Communications Books, Journals and other Communications References.

#### MCQ Topic Outline included in ECE Board Exam Syllabi

• MCQ in Basic Principles of Microwave Communications
• MCQ in Electro-Optics
• MCQ in Photonics
• MCQ in Optoelectronics
• MCQ in Electromagnetics
• MCQ in Avionics, Aerospace, Navigational and Military Applications
• MCQ in Medical Electronics
• MCQ in Cybernetics
• MCQ in Biometrics

#### Continue Practice Exam Test Questions Part 10 of the Series

451. Indicate which of the following frequencies cannot be used for reliable beyond-the-horizon terrestrial communications without repeaters:

a. 20 kHz

b. 15 MHz

c. 900 MHz

d. 12 GHz

Solution:

452. A ship-to-ship communications system is plagued by fading. The best solution seems to be the use of

a. A more directional antenna

c. Frequency diversity

d. Space diversity

Solution:

453. A range of microwave frequencies more easily passed by the atmosphere than are the others is called a

a. Window

b. Critical frequency

c. Gyro frequency range

d. Resonance in the atmosphere

Solution:

454. Frequencies in the UHF range propagate by means of

a. Ground waves

b. Sky waves

c. Surface waves

d. Space waves

Solution:

455. Tropospheric scatter is used with frequencies in the following range:

a. HF

b. VHF

c. UHF

d. VLF

Solution:

456. When microwave signals follow the curvature of the earth, this is known as

b. Ducting

c. Tropospheric scatter

d. Ionospheric reflection

Solution:

457. Helical antennas are often used for satellite tracking at VHF because of

a. Troposcatter

b. Superrefraction

c. Ionospheric refraction

Solution:

458. _______________ consists basically of a thin film strip in intimate contact with one side of a flat dielectric substrate, with a similar thin-film ground plane conductor on the other side of the substrate.

a. Strip line

b. Lecher wire

c. Microstrip

d. Stub

Solution:

459. Waveguide is a

a. Device used to determine the wavelength of a signal

b. Hollow metal tube used for transmission of microwave energy

c. Plastic tubular transmission line for high RF network

d. Braided wire used for transmission of HF

Solution:

460. Transmission lines which can convey electromagnetic waves only in higher order modes are usually called

a. Coaxial cable

b. Twisted pair

c. Power lines

d. Waveguides

Solution:

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

a. Circular

b. Ridge

c. Rectangular

d. Elliptical

Solution:

462. A signal propagated in a waveguide has a full wave of electric intensity change between the two farther 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:

463. When a particular mode is excited in a waveguide, there 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:

464. The wavelength of a wave in a waveguide

a. Is greater than in free space

b. Depends on waveguide dimensions and free space wavelength

c. Is inversely proportional to the phase velocity

d. Is directly proportional to the group velocity

Solution:

465. When electromagnetic waves are propagated in a waveguide, they

a. Travel along the broader walls of the guide

b. Are reflected from walls but not travel along them

c. Travel through the dielectric without touching the walls

d. Travel along the 4 walls of the waveguides

Solution:

466. When microwave signals follow the curvature of the earth, this is known as

b. Deducting

c. Tropospheric Scatter

d. Ionospheric Reflection

Solution:

467. A waveguide mode in which there is no component of electric field in the direction of propagation given in the British European standards.

a. H-mode

b. E-mode

c. TE mode

d. M-mode

Solution:

468. The extra strength needed in order to assure that enough signal reaches the receiving antenna and must be made available to compensate for fades; computed as the difference between the received signal strength and the threshold level

b. Threshold Level

c. Noise Figure

d. RSL

Solution:

469. The use of redundant system to reduce the effects of multipath fading is

a. Combining

b. Modulation

c. Multiplexing

d. Diversity

Solution:

470. A profile graph of the microwave energy path

a. Shows the cross section of the earthโs surface

b. Determines LOS or site technical feasibility

c. Determines the actual clearance, antenna heights and system reliability

d. All of the preceding

Solution:

471. In locating microwave relay stations, the systems designer must consider

a. Terrain obstructions and reflection points

b. Site security and navigational hazards

c. Availability of power, water source and accessible roads

d. All of the above

Solution:

472. A microwave path over which radio waves barely touches the obstruction is called

a. Line of Sight

b. Obstructed Path

c. Grazing Path

d. Crooked Path

Solution:

473. What is the function of regenerative repeater?

a. To eliminate bias distortion

c. To reduce required signal levels

d. To reshape the pulses after they have become distorted

Solution:

474. A situation when there is no change in attenuation or โno gain, no lossโ occurs when ________ % of the first Fresnel radius clears a path obstruction in microwave systems.

a. 45%

b. 60%

c. 75%

d. 85%

Solution:

475. ____________ are concentric circular zones about a direct path of a microwave signal called Huygenโs radiation center, forming an imaginary solid called an ellipsoid __________.

a. Temperature zone

b. Skip zone

c. Fresnel zone

d. Fraunhoffer zone

Solution:

476. Waveguides are used mainly for microwave transmission because

a. They depend on straight line propagation

b. Losses are heavy at lower frequencies

c. They are bulky at lower frequencies

d. No generator is powerful enough to excite them

Solution:

477. A waveguide assembly that lets the radar transmitter and receiver share an antenna is called

a. Translator

b. Diplexer

c. Flip-flop

d. duplexer

Solution:

478. ________________ is a graph wherein the terrain in which the microwave beam should traverse.

a. Topograph

c. Fresnel graph

d. Net path graph

Solution:

479. The Fresnel zone is the circular zone about the _______ path.

a. Reflected

b. Direct

c. Diffracted

d. Refracted

Solution:

480. The radius in the circular zone is in the first Fresnel zone when the reflected path is _______ longer than the direct path.

a. ฮป/2

b. ฮป

c. ฮป/4

d. ฮป/8

Solution:

481. At __________ of the first Fresnel zone is a condition where there is no gain and no loss.

a. 0.5

b. 0.6

c. 0.7

d. 0.8

Solution:

482. The weakest signal the receiver could accept to be considered satisfactory.

a. Threshold

c. RSL

d. NPL

Solution:

483. The frequency band from 8 to 12 GHz is known as the band.

a. C

b. Ku

c. X

d. Ka

Solution:

484. The difference between the Received Signal Level and the FM Improvement Threshold

a. System Gain

b. Noise Threshold

d. Reliability

Solution:

485. A Fade Margin of 28 dB has a reliability of

a. 99%

b. 99.9%

c. 99.99%

d. 99.999%

Solution:

486. Topographical maps are used for microwave communications systems design because _________ are shown, thereby elevations are known.

a. Latitudes

b. Longitudes

c. Contour lines

d. Scales

Solution:

487. The dominant mode in a rectangular waveguide.

a. TEM

b. TE1,1

c. TE1,0

d. TM1,1

Solution:

488. The velocity of a resultant wave as it travels through the waveguide.

a. Speed of light

b. Group velocity

c. Phase velocity

d. Incident velocity

Solution:

489. The principal mode for a circular waveguide.

a. TE1,0

b. TM2,0

c. TE1,1

d. TEM

Solution:

490. A type of waveguide that reduces the cutoff wavelength, increases bandwidth and allows for a variation of the characteristics impedance.

a. Ridge

b. Rectangular

c. Tee

d. Twisted

Solution:

491. The subscript which indicates the number of ฮป/2โ s along the waveguide height.

a. m

b. n

c. a

d. b

Solution:

492. The international equivalent of the TE mode

a. H

b. E

c. Z

d. TEM

Solution:

493. The smallest free space wavelength that is just unable to propagate in the waveguide under given conditions.

a. Guide

b. Phase

c. Cut-off

d. Group

Solution:

494. The characteristic wave impedance of a waveguide in the TE mode is _______ that of the TM mode.

a. Equal to

b. Higher than

c. Lower than

d. NOTA

Solution:

495. The following are methods of exciting waveguides except

a. Slot coupling

b. Antennas

c. Flanges

d. Direct coupling

Solution:

496. Higher order mode-waveguides are not used in practice because they have ______ cut-off frequencies.

a. Low

b. High

c. Indeterminate

d. Fixed

Solution:

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

a. Elliptical

b. Flexible

c. Coaxial

d. Ridged

Solution:

498. A piston attenuator is a

a. Vane attenuator

b. Waveguide below cut-off

c. Mode filter

d. Flap attenuator

Solution:

499. Which of the following waveguide tuning components is not easily adjustable?

a. Screw

b. Stub

c. Iris

d. Plunger

Solution:

500. Which of the following is not a waveguide termination component?

a. Tapered pyramid

b. Post

c. Tapered resistance card

d. Stepped resistance card

Solution:

#### Questions and Answers in Microwave Communications and Principles Series

Following is the list of multiple choice questions in this brand new series:

MCQ in Microwave Communications
PART 1: MCQ from Number 1 โ 50                        Answer key: PART 1
PART 2: MCQ from Number 51 โ 100                   Answer key: PART 2
PART 3: MCQ from Number 101 โ 150                 Answer key: PART 3
PART 4: MCQ from Number 151 โ 200                 Answer key: PART 4
PART 5: MCQ from Number 201 โ 250                 Answer key: PART 5
PART 6: MCQ from Number 251 โ 300                 Answer key: PART 6
PART 7: MCQ from Number 301 โ 350                 Answer key: PART 7
PART 8: MCQ from Number 351 โ 400                 Answer key: PART 8
PART 9: MCQs from Number 401 โ 450                 Answer key: PART 9
PART 10: MCQs from Number 451 โ 500                 Answer key: PART 10

### Complete List of MCQ in Communications Engineering per topic

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