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# MCQ in Microwave Communications Part 8 | ECE Board Exam

This is the Multiples Choice Questions Part 8 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 8 of the Series

351. What are limits of microwaves?

a) 1 โ 25,000 GHz

b) 1 โ 50,000 GHz

c) 1 โ 75,000 GHz

d) 1 โ 100,000 GHz

Solution:

352. The following transmission lines are used for microwave frequencies, except:

a) waveguide

c) coax

d) stripline

Solution:

353. How much must a waveguide be?

a) over a half-wave

b) over a quarter-wave

c) over a wavelength

d) over three-fourths of a wavelength

Solution:

354. How high must a waveguide be?

a) over a wavelength

b) over a quarter wave

c) over a half wave

d) over two wavelengths

Solution:

355. What is the designation of the lowest-frequency microwave band?

a) V band

b) X band

c) Ku band

d) L band

Solution:

356. What is the designation of the highest-frequency microwave band?

a) R band

b) Ka band

c) V band

d) L band

Solution:

357. What is reduced by using choke flanges?

a) refraction

b) reflection

c) absorption

d) cancellation

Solution:

358. What is the name of the microwave transmission line that is used in printed circuits?

a) microstrip

b) coax

d) twisted pair

Solution:

359. Where is the resistive load placed in a directional coupler?

a) front end of the primary

b) front end of the secondary

c) back end of the primary

d) back end of the secondary

Solution:

360. One of the following is a type of bolometer

a) calorimeter

b) thermocouple

c) barreter

d) carreter

Solution:

361. Why are bolometers not used to detect modulation?

a) thermal sluggishness

b) inefficiency

c) less accurate

d) less precise

Solution:

362. The advantage of a resonant cavity over a hairpin tank?

a) lesser Q

b) wider bandwidth

c) higher Q

d) efficiency

Solution:

363. What type of coupling is used between a waveguide and a waveguide wavemeter?

a) loop antenna

b) quarterwave antenna

c) hole

d) E probe

Solution:

364. Which microwave tube has a repeller?

a) TWT

b) Klystron

c) Magnetron

d) BWO

Solution:

365. Which microwave tube has a series of cavities?

a) magnetron

b) klystron

c) TWT

d) BWO

Solution:

366. Which microwave tube has a helix

a) klystron

b) magnetron

c) multicavity klystron

d) BWO

Solution:

367. Which microwave tube has a horseshoe magnet?

a) magnetron

b) klystron

c) TWT

d) BWA

Solution:

368. What is the advantage of a gridless klystron

a) power input

b) gain

c) attenuator

d) power output

Solution:

369. Which vacuum tube do you think oscillate at the highest frequency

a) Magnetron

b) Gunn

c) Klystron

d) BWO

Solution:

370. How would a balun be used to change 200 ohms to 50 ohms?

a) use a higher turns ratio

b) use a higher frequency

c) reverse it

d) use low frequency

Solution:

371. How could a balun change 100 ohms to 900 ohms

a) use 3:1 turns ratio

b) use 1:3 turns ratio

c) use 9:1 turns ratio

d) use 1:9 turns ratio

Solution:

372. How high a frequency can transistor generate?

a) above 10 GHz

b) above 5 GHz

c) above 2 GHz

d) above 7.8 GHz

Solution:

373. What is the microwave application of a varactor?

a) mixer

b) frequency multiplier

c) demodulator

d) demultiplexer

Solution:

374. What diode does better than varactor in microwave frequencies?

a) step recovery

b) tunnel

c) PIN

d) Gunn

Solution:

375. The following diodes can generate microwave AC except:

a) Tunnel

b) LSA

c) IMPATT

d) Magnetron

Solution:

376. For what are PIN diodes used in microwave?

a) mixers

b) modulators

c) oscillators

d) amplifier

Solution:

377. What is the other name for LSA diodes?

a) negative resistance

b) bulk-effect

c) tunneling effect

d) time-space

Solution:

378. What is the advantage of LSA over a Gunn Diode?

a) more efficient

b) higher power

c) less noise

d) higher frequency

Solution:

379. What is wrong with the term Gunn Diode?

a) not a gun

b) not a semiconductor

c) not a diode

d) should be spelled with single โnโ

Solution:

380. What is important property do ferrites have which is used as a switch?

b) resonance absorption

c) magnetic properties

d) high curie temperature

Solution:

381. Which is used in circulators?

a) resonance absorption

b) magnetic properties

c) ion resonance

Solution:

382. What is the advantage of using a circulator with two transmitter and two receivers?

a) many antennas

b) less interference

c) easy coupling

d) one antenna only

Solution:

383. To what must the fourth port be connected in a tunnel diode amplifier?

a) resistor

b) inductor

c) capacitor

d) impedance

Solution:

384. To what must the third port be connected in a multiplexer circulator

a) reflecting short circuit

b) absorbing short circuit

c) reflecting open circuit

d) absorbing open circuit

Solution:

Solution:

386. In what distance unit are marine radars calibrated?

a) statute miles

b) kilometers

c) nautical miles

d) feet

Solution:

387. What time unit is the equivalent of a radar mile?

a) 12.3 microseconds

b) 6.8 microseconds

c) 4.5 microseconds

d) 7.1 microseconds

Solution:

388. In what frequency band does marine radar operate?

a) 9.5 GHz S band

b) 3 GHz X band

c) 9.5 GHz Ku band

d) 3 GHz S band

Solution:

389. To what two circuits would a radar timer circuit feed signals?

a) modulator and mixer

b) amplifier and circulator

c) modulator and circulator

d) amplifier and modulator

Solution:

390. What is the target display on a CRT called?

a) crosshair

b) blip

c) center spot

d) round

Solution:

391. What is the main bang on a PPI radar set?

a) blip

b) center spot

c) bearing

d) round

Solution:

392. What is the ability to separate adjacent equidistant targets called?

a) bearing resolution

b) narrow bandwidth

c) high frequency

d) shorter wavelength

Solution:

393. What is the approximate rotational rate of a radar antenna?

a) 20 rpm

b) 5 rpm

c) 25 rpm

d) 10 rpm

Solution:

394. How is radar CRTs differ from TV?

a) square

b) round

c) rectangular

d) trapezoidal

Solution:

395. What circuits make up the radar transmitter?

a) multivibrator

b) trapezoidal oscillator

c) sine wave generator

d) blocking oscillator

Solution:

396. What type of oscillator determines the PRR?

a) blocking

b) pulse

c) square

d) blocking or pulse

Solution:

397. What other circuit might be used as an oscillator that determines the PRR?

a) trapezoidal generator

b) unbalanced multivibrator

c) bistable multivibrator

d) sinewave generator

Solution:

398. Why are hydrogen-gas thyratrons used in radar?

a) fast-ionize

b) cheaper

c) accurate

d) efficient

Solution:

399. What is the other name for a pulse-forming network in radars?

a) tuned circuit

b) oscillators

c) delay line

d) capacitive circuits

Solution:

400. What determines the PRR in odd-time radar sets?

a) tuned circuit frequency

b) oscillator frequency

c) spark gap speed

d) MOPA transmitter time

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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