MCQs in Microwave Communications Part XI

This is the Multiples Choice Questions Part 11 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.

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:

Microwave Communications MCQs

PART 1: MCQs from Number 1 – 50                        Answer key: PART I

PART 2: MCQs from Number 51 – 100                   Answer key: PART II

PART 3: MCQs from Number 101 – 150                 Answer key: PART III

PART 4: MCQs from Number 151 – 200                 Answer key: PART IV

PART 5: MCQs from Number 201 – 250                 Answer key: PART V

PART 6: MCQs from Number 251 – 300                 Answer key: PART VI

PART 7: MCQs from Number 301 – 350                 Answer key: PART VII

PART 8: MCQs from Number 351 – 400                 Answer key: PART VIII

PART 9: MCQs from Number 401 – 450                 Answer key: PART IX

SEE: More Questions and Answers in Microwave Communications

PART 11: MCQs from Number 501 – 550                 Answer key: PART XI

Continue Practice Exam Test Questions Part XI of the Series

501. What microwave component can sample part of the power travelling through the waveguide?

• a. Directional coupler
• b. Magic tee
• c. Circulator
• d. Re-entrant cavity

502. The following are gases used for LASER’s except

• a. Helium
• b. Neon
• c. Argon
• d. ruby

503. Also known as the optical maser

• a. Ruby maser
• b. LASER
• c. Quantum mechanics
• d. GaAs maser

504. Paramagnetic means _____________ magnetic

• a. Almost
• b. Fully
• c. Slightly
• d. Electro

505. Tuning the ruby maser is done by adjusting the _________ to alter the energy level of the ferrous chromium.

• a. Electric field
• b. Magnetic field
• c. Pumping of electrons
• d. Electromagnetic field

506. To overcome the very narrow bandwidth in ruby maser, _______ is used.

• a. Magnetron
• b. TWT
• c. IMPATT diode
• d. Gunn diode

507. The following are applications of masers except

• a. Radioastronomy
• b. Radiotelescope
• c. Radar
• d. ET communications

508. A parametric amplifier is a device which amplifies signal by varying the

• a. Resistance
• b. Reactance
• c. Magnetic field
• d. Electric field

509. The following are parts of the parametric amplifier except

• a. Idling circuit
• b. Pump circuit
• c. Tuned circuit
• d. Filter circuit

510. The number of cavities in a magnetron used in practice.

• a. 4
• b. 6
• c. 8
• d. 10

511. Changing the anode voltage to change the velocity of the electrons in a magnetron tube

• a. Frequency pushing
• b. Frequency pulling
• c. Strapping
• d. Pumping

512. The lowest frequency that will propagate through the waveguide while operating in a particular mode.

• a. Critical frequency
• b. Cut-off frequency
• c. MUF
• d. UHF

513. The mode of a waveguide where there is no component of magnetic field in the direction of propagation

• a. TE
• b. TM
• c. H
• d. TEM

514. The following are slow wave structures used to retard the RF field in a TWT except

• a. Helix
• b. Attenuator
• c. Waveguide coupled cavity
• d. NOTA

515. A rectangular waveguide is 5.1 cm by 2.4 cm. The cut-off frequency for the dominant mode is

• a. 2.94 GHz
• b. 6.25 GHz
• c. 664 MHz
• d. 57.7 GHz

516. Calculate the cut-off wavelength, the guide wavelength and the characteristic impedance of a circular waveguide whose internal diameter is 4 cm for a 10 GHz signal propagated in it in the dominant mode. (kr = 1.84)

• a. 6.83 cm, 3 cm, 420ῼ
• b. 3 cm , 6.83 cm, 420 ῼ
• c. 6.83 cm, 3.34 cm, 420 ῼ
• d. 6.83 cm, 3.34 cm, 338 ῼ

517. A wave is propagated in a parallel plane waveguide. The frequency is 6 GHz and the plane separation is 3 cm. The cut-off wavelength for the dominant mode, the group and phase velocities are

• a. 5 cm, 166 Mm/sec,543 Mn/sec
• b. 6 cm, 166 Mm/sec,543 Mn/sec
• c. 6 cm, 543 Mm/sec,166 Mn/sec
• d. 5 cm, 543 Mm/sec,166 Mn/sec

518. If the MTBF of a communication circuit is 20,000 hours and its MTTR is 5 hours, what is its unavailability?

• a. 0.00025
• b. 99.975%
• c. 0.25 %
• d. 00.975%

519. What would be the ERP, in watts if the transmitter output is 30 dBm and the transmission line loss is 20 dB and the antenna connected to it has a power gain of 60 dB?

• a. 10,000 watts
• b. 1000 watts
• c. 100 watts
• d. 10 watts

520. Also referred to as the Transferred Electron Device

• a. Magnetron
• b. TWT
• c. Gunn diode
• d. APD

521. Also known as the Esaki diode

• a. Gunn
• b. Tunnel
• c. IMPATT
• d. PIN diode

522. The following are negative resistance amplifiers except

• a. Tunnel
• b. Gunn
• c. IMPATT
• d. PIN diode

523. Regarded as the oldest semiconductor device

• a. Shottky Barrier diode
• b. PIN diode
• c. Point contact diode
• d. Triode

524. Also called the hot electron diode

• a. PIN diode
• b. ESBAR
• c. APD
• d. Gunn diode

525. Also called tunnel rectifiers

• a. Backward diode
• b. Schottky barrier diode
• c. APD
• d. PIN diode

526. Varactors are variable __________ diode.

• a. Reactance
• b. Capacitance
• c. Inductance
• d. Resistance

527. Diodes designed to store energy in their capacitance during forward bias and generates harmonics in the reverse bias.

• a. Step recovery
• b. Gunn
• c. APD
• d. IMPATT

528. A cross between the TWT and the magnetron in its operation

• a. CFA
• b. BWO
• c. EIA
• d. Twystron

529. The following are parts of a multicavity klystron except

• a. Buncher cavity
• b. Catcher cavity
• c. Cathode
• d. Attenuator

530. The very first microwave transistors

• a. GaAs FET
• b. Si BJT
• c. MIC
• d. NOTA

531. The most common microwave FET which is also known as the MESFET

• a. Dual GaAs FET
• b. Si BJT
• c. MIC
• d. Schottky Barrier Gate

532. It looks like a shorter, thicker TWT

• a. CFA
• b. BWO
• c. EIA
• d. Twystron

533. A Twystron is a hybrid combination of

• a. TWT and Magnetron
• b. TWT and Klystron
• c. TWT and Ubitron
• d. TWT and gyrotron

534. A multicavity klystron with interconnected multigap cavities

• a. TWT
• b. Twystron
• c. EIA
• d. Gyrotron

535. SAW propagate in

• a. GaAs
• b. InP
• c. Stripline
• d. Quartz crystal

536. The output from a laser is monochromatic; this means that it is

• a. Infrared
• b. Narrow beam
• c. Polarized
• d. Single frequency

537. The ruby laser differs from the ruby maser in that the former

• a. Does not require pumping
• b. Needs no resonator
• c. Is an oscillator
• d. Produces much lower powers

538. The transmission system using two ground planes

• a. Microstrip
• b. Elliptical waveguide
• c. Parallel wire line
• d. Stripline

539. A BWO is based on the

• a. Rising sun magnetron
• b. CFA
• c. Coaxial magnetron
• d. TWT

540. One of the following is unlikely to be used as a pulsed device

• a. Multicavity klystron
• b. BWO
• c. CFA
• d. TWT

541. A microwave tube amplifier uses an axial magnetic field and a radial electric field

• a. Reflex klystron
• b. Coaxial magnetron
• c. TW magnetron
• d. CFA

542. The attenuator is used in the TWT to

• a. Help bunching
• b. Prevent oscillation
• c. Prevent saturation
• d. Increase gain

543. The glass tube of a TWT may be coated with aquadag to

• a. Help focusing
• b. Provide attenuation
• c. Improve bunching
• d. Increase gain

544. The cavity magnetron uses strapping to

• a. Prevent mode jumping
• b. Prevent cathode back heating
• c. Ensure bunching
• d. Improve the phase focusing effect

545. Compared with equivalent transmission lines, 3-GHz waveguides (indicate false statement)

• a. Are less lossy
• b. Can carry higher powers
• c. Are less bulky
• d. Have lower attenuation

546. Indicate the false statement. When the free-space wavelength of a signal equals the cut-off wavelength of the guide

• a. The group velocity of the signal becomes zero
• b. The phase velocity of the signal becomes infinite
• c. The characteristic impedance of the guide becomes infinite
• d. The wavelength within the waveguide becomes infinite

547. A disadvantage of microstrip with respect to stripline circuits is that the former

• a. Do not lend themselves to printed-circuit techniques
• b. Are more likely to radiate
• c. Are bulkier
• d. Are more expensive and complex to manufacture

548. In order to couple two generators to a waveguide system without coupling them to each other, one could not use a

• a. Rat-race
• b. E-plane T
• c. Hybrid ring
• d. Magic T

549. 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

550. For handling high powers, the best transmission medium is

• a. Stripline
• b. Microstrip
• c. Rectangular waveguide
• d. Coaxial line

Complete List of MCQs in Communications Engineering per topic

Series of Multiple Choice Questions in Electronics Systems and Technologies

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