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 IX of the Series
401. What is used to carry RF energy from magnetron to antenna in a radar set?
- a) helix
- b) parallel wireline
- c) coax
- d) waveguide
402. What is the method of illuminating a parabolic reflector with RF?
- a) horn
- b) cassegrain
- c) helix
- d) coax
403. How would a radar reflector be parabolic-shaped
- a) circularly
- b) vertically
- c) horizontally
- d) none of these
404. In what way are radar emissions similar to microwave ovens?
- a) can transmit
- b) can receive
- c) can cook
- d) can transceiver
405. To what tube is a dc keep-alive voltage applied?
- a) Oscillator
- b) Transmit-Receive Mixer
- c) Circulator
- d) Isolator
406. In radar, if the mixer diode burns out, what are replaced?
- a) tube
- b) mixer
- c) antenna
- d) diode
407. What is the cavity between magnetron and mixer cavity called?
- a) ATR
- b) TR
- c) Transmit
- d) Receive
408. Radar receivers use what Ifs
- a) 20 MHz and lower
- b) 10 MHz and higher
- c) 30 MHz or higher
- d) 10 MHz and lower
409. What kind of local oscillators does a radar receiver use?
- a) klystron
- b) magnetron
- c) LSA
- d) TWT
410. What solid-state types might be used as a radar receiver?
- a) Gunn diode
- b) Tunnel diode
- c) Hot carrier diode
- d) Step recovery diode
411. What does an ATR tube aid?
- a) transmitting
- b) receiving
- c) both transmitting and receiving
- d) neither transmitting and receiving
412. To what is the AFC voltage applied in a klystron?
- a) cathode
- b) grid
- c) plate
- d) any of these
413. Sea return is the control that desentisizes a radar receiver for _____
- a) 5 – 10 microseconds
- b) 15 – 20 microseconds
- c) 10 – 15 microseconds
- d) 20 – 25 microseconds
414. In radars, how is blooming prevented?
- a) limit modulation
- b) video signal
- c) limit the carrier signal
- d) limit the audio signal
415. How is brilliance controlled in radars?
- a) audio gain
- b) IF gain
- c) RF gain
- d) video gain
416. How is sensitivity limited in radars?
- a) RF gain
- b) video gain
- c) audio gain
- d) IF gain
417. How much intensifying pulse is used in radars?
- a) Just enough to produce light flicker on screen
- b) should be high to produce light flicker on screen
- c) should be low to produce light flicker on screen
- d) any amount of intensifying pulse will do
418. If echo signals are developed as negative pulses, to what part of the CRT would they be fed in radar?
- a) anode
- b) grid
- c) cathode
- d) 2nd grid
419. What starts the range-marker circuit ringing in radars?
- a) intensifying pulse
- b) IF gain
- c) AC signal
- d) Carrier signal
420. Why is a selsyn pair not too successful for radar antenna synchronization?
- a) constant lead angle
- b) variable lag angle
- c) constant lag angle
- d) variable lead angle
421. What is fed to the rotor of a selsyn motor?
- a) power-line AC
- b) DC source
- c) A pulsating DC
- d) None
422. What is fed to the rotor selsyn generator?
- a) none
- b) power-line AC
- c) DC source
- d) A pulsating DC
423. What is fed to a control transformer rotor?
- a) A pulsating DC
- b) power-line AC
- c) DC source
- d) none
424. What is used to indicate the bow of the ship on the CRT?
- a) tail flash
- b) body flash
- c) heading flash
- d) none
425. When is an echo box used on ships?
- a) testing only
- b) direction finding
- c) auto alarm
- d) ship detection
426. What qualification must a person have before he is eligible to make repairs to a radar set?
- a) NTC endorsement
- b) repair license
- c) repair endorsement
- d) radar endorsement
427. What is the advantage of using Doppler radar?
- a) shows only moving target
- b) shows stationary target
- c) shows both moving and stationary target
- d) produce blips with stationary targets
428. How would Doppler radar give speed indications?
- a) adjust output burst
- b) correct RF carrier output
- c) switch amplitude detector
- d) calibrate discriminator output
429. What is another application of Doppler radar?
- a) distance between radar and stationary target
- b) ground speed indicator
- c) ground missile indicator
- d) enemy base station
430. Why are signal nulls used in Radio Direction Finders work?
- a) sharper than maximums
- b) sharper than minimums
- c) duller than maximums
- d) duller than minimums
431. How many are signal nulls in one loop rotation Radio Direction Finders?
- a) 3
- b) 4
- c) 5
- d) 2
432. Under what conditions do the horizontal portions of a loop pick up difference currents in RDF?
- a) ground waves
- b) sky waves
- c) space waves
- d) direct waves
433. The method of balancing a loop used in RDF?
- a) Capacitor to ground
- b) Capacitor to sense antenna
- c) Sense antenna to one side of loop
- d) Any of these
434. For what are unidirectional readings used in loops for RDF?
- a) resolve a 180 degrees ambiguity
- b) resolve a 90 degrees ambiguity
- c) resolve a 360 degrees ambiguity
- d) resolve a 270 degrees ambiguity
435. What kind of antenna is a sense antenna used in RDF?
- a) circular
- b) vertical
- c) horizontal
- d) any of these
436. In RDF, what happens to a radio wave path as it moves outward across a coastline as less than 90 degrees?
- a) bends away from the shore
- b) travels along the shore
- c) bends towards shore
- d) travels across the shore
437. What is the result of antenna effect in RDF?
- a) rotated 90 degrees
- b) nulls shift
- c) decreases land effect
- d) coastline refraction
438. What is the result of re-radiation of signals in RDF?
- a) great circle error
- b) non-opposite minimums
- c) polarization errors
- d) nulls shifted
439. What causes night effect in direction finding?
- a) ground plus space wave
- b) sky plus space wave
- c) ground plus sky waves
- d) ground wave alone
440. At what time of the day is direction finder bearings least accurate
- a) sunset
- b) sunrise
- c) mid-day
- d) sunset and sunrise
441. At what angles are quadrantal errors maximum in direction finding
- a) 45 degrees
- b) 90 degrees
- c) 180 degrees
- d) 270 degrees
442. How are quadrantal errors corrected?
- a) 330 degrees
- b) 360 degrees
- c) 315 degrees
- d) 215 degrees
443. How is it that none of the 120-550 kHz ADF circuits are tuned to the desired station?
- a) narrowband amplifiers
- b) broadband amplifiers
- c) IF amplifiers
- d) Mixers
444. What is the only hand-tuned circuit in the ADF?
- a) 3125-kHz signal local oscillator
- b) 4125-kHz signal local oscillator
- c) 2182-kHz signal local oscillator
- d) 2230-kHz signal local oscillator
445. What forms the error signal that actuates the ADF servo-motor?
- a) 75-Hz carrier
- b) 114-Hz carrier
- c) 114-Hz sideband
- d) 75-Hz sideband
446. Which ADF antenna is used for manual operation?
- a) parabolic antenna
- b) loop antenna
- c) half-wave dipole
- d) helical antenna
447. Which ADF antenna is used for simple receive operation?
- a) loop antenna
- b) sense antenna
- c) quarterwave antenna
- d) parabolic antenna
448. What is heard by earphones in the ADF?
- a) 3 kHz beat
- b) 1 kHz beat
- c) 2 kHz beat
- d) 5 kHz beat
449. If two bearing are determined from a radio beacon or station over a period of a few minutes, what else must be known to determine the ship’s position?
- a) speed
- b) elapses time
- c) ship’s course
- d) any of these
450. What important point regarding-loop RDF system maintenance?
- a) insulation at top of loop
- b) clean moving contacts
- c) oil bearing of loop
- d) any of these
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