
Online Questions and Answers Topic Outline
- MCQs in Basic Principles of Microwave Communications
- MCQs in Electro-Optics
- MCQs in Photonics
- MCQs in Optoelectronics
- MCQs in Electromagnetics
- MCQs in Avionics, Aerospace, Navigational and Military Applications
- MCQs in Medical Electronics
- MCQs in Cybernetics
- MCQs in Biometrics
MCQs in Microwave Communications and Principles Series
Following is the list of multiple choice questions in this brand new series:
Continue Practice Exam Test Questions Part X 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
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
- b. A broadband antenna
- c. Frequency diversity
- d. Space diversity
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
454. Frequencies in the UHF range propagate by means of
- a. Ground waves
- b. Sky waves
- c. Surface waves
- d. Space waves
455. Tropospheric scatter is used with frequencies in the following range:
- a. HF
- b. VHF
- c. UHF
- d. VLF
456. When microwave signals follow the curvature of the earth, this is known as
- a. The Faraday effect
- b. Ducting
- c. Tropospheric scatter
- d. Iosnospheric reflection
457. Helical antennas are often used for satellite tracking at VHF because of
- a. Troposcatter
- b. Superrefraction
- c. Ionospheric refraction
- d. The Faraday effect
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
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
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
461. In order to reduce cross-sectional dimensions, the waveguide to use is
- a. Circular
- b. Ridge
- c. Rectangular
- d. Elliptical
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
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
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
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
466. When microwave signals follow the curvature of the earth, this is known as
- a. Faraday Effect
- b. Deducting
- c. Tropospheric Scatter
- d. Ionospheric Reflection
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
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
- a. Fade Margin
- b. Threshold Level
- c. Noise Figure
- d. RSL
469. The use of redundant system to reduce the effects of multipath fading is
- a. Combining
- b. Modulation
- c. Multiplexing
- d. Diversity
470. A profile graph of the microwave energy path
- a. Shows the cross section of the earth’s surface
- b. Determines LOS or site technical feasibility
- c. Determines the actual clearance, antenna heights and system reliability
- d. All of the preceding
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
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
473. What is the function of regenerative repeater?
- a. To eliminate bias distortion
- b. To help in the loading of the telegraphs lines
- c. To reduce required signal levels
- d. To reshape the pulses after they have become distorted
474. A situation when there is no change in attenuation or “no gain, no loss” occurs when ________ % of the first Fresnel radius clears a path obstruction in microwave systems.
- a. 45%
- b. 60%
- c. 75%
- d. 85%
475. ____________ are concentric circular zones about a direct path of a microwave signal called Huygen’s radiation center, forming an imaginary solid called an ellipsoid __________.
- a. Temperature zone
- b. Skip zone
- c. Fresnel zone
- d. Fraunhoffer zone
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
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
478. ________________ is a graph wherein the terrain in which the microwave beam should traverse.
- a. Topograph
- b. Radio path profile
- c. Fresnel graph
- d. Net path graph
479. The Fresnel zone is the circular zone about the _______ path.
- a. Reflected
- b. Direct
- c. Diffracted
- d. Refracted
480. The radius in the circular zone is in the first Fresnel zone when the reflected path is _______ longer than the direct path.
- a. λ/2
- b. λ
- c. λ/4
- d. λ/8
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
482. The weakest signal the receiver could accept to be considered satisfactory.
- a. Threshold
- b. Fade margin
- c. RSL
- d. NPL
483. The frequency band from 8 to 12 GHz is known as the band.
- a. C
- b. Ku
- c. X
- d. Ka
484. The difference between the Received Signal Level and the FM Improvement Threshold
- a. System Gain
- b. Noise Threshold
- c. Fade Margin
- d. Reliability
485. A Fade Margin of 28 dB has a reliability of
- a. 99%
- b. 99.9%
- c. 99.99%
- d. 99.999%
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
487. The dominant mode in a rectangular waveguide.
- a. TEM
- b. TE1,1
- c. TE1,0
- d. TM1,1
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
489. The principal mode for a circular waveguide.
- a. TE1,0
- b. TM2,0
- c. TE1,1
- d. TEM
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
491. The subscript which indicates the number of λ/2’ s along the waveguide height.
- a. m
- b. n
- c. a
- d. b
492. The international equivalent of the TE mode
- a. H
- b. E
- c. Z
- d. TEM
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
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
495. The following are methods of exciting waveguides except
- a. Slot coupling
- b. Antennas
- c. Flanges
- d. Direct coupling
496. Higher order mode-waveguides are not used in practice because they have ______ cut-off frequencies.
- a. Low
- b. High
- c. Indeterminate
- d. Fixed
497. Indicate which of the following cannot be followed by the word “waveguide”
- a. Elliptical
- b. Flexible
- c. Coaxial
- d. Ridged
498. A piston attenuator is a
- a. Vane attenuator
- b. Waveguide below cut-off
- c. Mode filter
- d. Flap attenuator
499. Which of the following waveguide tuning components is not easily adjustable?
- a. Screw
- b. Stub
- c. Iris
- d. Plunger
500. Which of the following is not a waveguide termination component?
- a. Tapered pyramid
- b. Post
- c. Tapered resistance card
- d. Stepped resistance card
Post a Comment
Click to see the code!
To insert emoticon you must added at least one space before the code.