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 VII of the Series
301. A type of tee so-named because of the side arms shunting the E field for the TE modes, which is analogous to voltage in the transmission lines
- a) magic tee
- b) rat tee
- c) series tee
- d) shunt tee
302. Which one of the following waveguide tuning components is not easily adjustable?
- a) screw
- b) stub
- c) iris
- d) plunger
303. What type of waveguide is widely used?
- a) circular
- b) ridged
- c) flexible
- d) rectangular
304. A piston attenuator is a
- a) vane attenuator
- b) waveguide below cutoff
- c) mode filter
- d) flap attenuator
305. Waveguides act as _____.
- a) low-pass filter
- b) bandpass filter
- c) high-pass filter
- d) band-stop filter
306. Cylindrical cavity resonators are not used with klystron 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
307. In waveguides, if no component of the E field is in the direction of propagation the mode is said to be
- a) TE
- b) TM
- c) TEM
- d) TME
308. 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
309. The smallest free-space wavelength that is just unable to propagate in the waveguide
- a) cutoff wavelength
- b) cutoff frequency
- c) cutoff waveguide length
- d) cutoff phase
310. It is the minimum frequency of waves that can propagate through the waveguide
- a) cutoff frequency
- b) cutoff wavelength
- c) cutoff phase
- d) cutoff waveguide length
311. A common application of magnetrons is in
- a) Radar
- b) Satellites
- c) Two-way radio
- d) TV sets
312. In waveguides, it is the velocity at which the wave changes phase
- a) waveguide velocity
- b) group velocity
- c) phase velocity
- d) total velocity
313. 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
314. In waveguides, it is the velocity at which the wave propagates
- a) phase velocity
- b) group velocity
- c) total velocity
- d) waveguide velocity
315. 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
316. A common omnidirectional microwave antenna is the
- a) horn
- b) parabolic reflector
- c) helical
- d) bicone
317. The output of a helical antenna is
- a) vertically polarized
- b) horizontally polarized
- c) circularly polarized
- d) linearly polarized
318. For some applications, circular waveguides may be preferred to rectangular ones because of
- a) the smaller the cross section needed at any frequency
- b) lower attenuation
- c) freedom from spurious modes
- d) rotation of polarization
319. A helical antenna is made up of a coil and a
- a) director
- b) reflector
- c) dipole
- d) horn
320. In a klystron amplifier, velocity modulation of the electron beam is produced by the
- a) collector
- b) catcher cavity
- c) cathode
- d) buncher cavity
321. Increasing the diameter of a parabolic reflector causes which of the following:
- a) decreased beamwidth
- b) increased gain
- c) none of the above
- d) decreased beamwidth and increased gain
322. For low attenuation, the best transmission medium is
- a) flexible waveguide
- b) ridged waveguide
- c) rectangular waveguide
- d) coaxial line
323. Low-power Gunn diodes are replacing
- a) Reflex klystron
- b) TWTs
- c) Magnetrons
- d) Varactor diodes
324. One of the reasons why vacuum tubes eventually fail at microwave frequencies is that their
- a) noise figure increases
- b) transmit time becomes too short
- c) shunt capacitive reactances becomes too large
- d) series inductance reactances becomes too small
325. A rectangular waveguide has a width of 1 inch and a height of 0.6 inch. Its cutoff frequency is
- a) 2.54 GHz
- b) 3.0 GHz
- c) 5.9 GHz
- d) 11.8 GHz
326. The TWT is sometimes preferred to the multicavity klystron amplifier, because the former
- a) is more efficient
- b) has a greater bandwidth
- c) has a higher number of modes
- d) produces higher output power
327. The most common cross section of a waveguide is a
- a) square
- b) circle
- c) triangle
- d) rectangle
328. The cavity magnetron uses strapping to
- a) prevent mode jumping
- b) prevent cathode back-heating
- c) ensure bunching
- d) improve the phase-focusing effect
329. Signal propagation in a waveguide is by
- a) electrons
- b) electric and magnetic fields
- c) holes
- d) air pressure
330. The dominant mode in most waveguides is
- a) TE 0,1
- b) TE 1,2
- c) TM 0,1
- d) TM 1,1
331. Periodic permanent-magnet focusing is used with TWTs to
- a) allow pulsed operation
- b) improve electron bunching
- c) avoid the bulk of electromagnet
- d) allow coupled-cavity operation at the highest frequencies
332. A popular microwave mixer diode is the
- a) Gunn
- b) Varactor
- c) Hot carrier
- d) IMPATT
333. A magnetron whose oscillating frequency is electronically adjustable over a wide range is called a
- a) coaxial magnetron
- b) dither-tune magnetron
- c) frequency-agile magnetron
- d) VTM
334. The main benefit of using microwave is
- a) lower-cost equipment
- b) sampler equipment
- c) greater transmission distances
- d) more spectrum space for signals
335. Which diode is a popular microwave oscillator?
- a) IMPATT
- b) Gunn
- c) Varactor
- d) Schottly
336. Which of the following is not a disadvantage of microwave?
- a) higher cost equipment
- b) line-of-sight transmission
- c) conventional components are not usable
- d) circuits are more difficult to analyze
337. Which of the following is a microwave frequency?
- a) 1.7 MHz
- b) 750 MHz
- c) 0.98 MHz
- d) 22 GHz
338. In a TWT, the electron beam, is density-modulated by a
- a) Permanent magnet
- b) Modulation transformer
- c) Helix
- d) Cavity resonator
339. Which of the following is not a common microwave application?
- a) radar
- b) mobile radio
- c) telephone
- d) spacecraft communications
340. Indicate the false statement. Transit time in microwave tubes will be reduced if
- a) the electrodes are brought closer together
- b) a higher node current is used
- c) multiple or coaxial loads are used
- d) the anode voltage is made larger
341. Coaxial cable is not widely used for long microwave transmission lines because of its
- a) high loss
- b) high lost
- c) large size
- d) excessive radiation
342. The main advantage of the TWT over a klystron for microwave amplification is
- a) lower cost
- b) smaller size
- c) higher power
- d) wider bandwidth
343. A magnetic field is used in the cavity magnetron to
- a) prevent anode current in the absence of oscillations
- b) ensure that the oscillations are pulsed
- c) help in focusing the electron beam, thus preventing spreading
- d) ensure that the electrons will orbit around the cathode
344. A waveguide has a cutoff frequency of 17 GHz. Which of the signals will not be passed by the waveguide?
- a) 15 GHz
- b) 18 GHz
- c) 22 GHz
- d) 25 GHz
345. When the electric field in a waveguide is perpendicular to the direction of wave propagation, the mode is said to be
- a) vertical polarization
- b) transverse electric
- c) horizontal polarization
- d) transverse magnetic
346. The TWT is sometimes preferred to the magnetron as a radar transmitter output tube because it is
- a) capable of longer duty cycle
- b) a more efficient amplifier
- c) more broadband
- d) less noisy
347. A magnetic field is introduced into a waveguide by a
- a) probe
- b) dipole
- c) stripline
- d) capacitor
348. A reflex klystron is used as a/n
- a) amplifier
- b) oscillator
- c) mixer
- d) frequency multiplier
349. Indicate the false statement: Manganese ferrite may be used as a
- a) circulator
- b) isolator
- c) garnet
- d) phase shifter
350. Indicate the false statement. Klystron amplifiers may use intermediate cavities to
- a) prevent oscillations that occur in two-cavity klystron
- b) increase the bandwidth of the device
- c) improve the power gain
- d) increase the efficiency of the klystron
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