Which is not a type of horn antenna design for microwave frequencies?

  Parabolic hornCircular hornPyramidal hornSectoral horn

Cassegrain feed to a paraboloid antenna involves a  Dipole antenna

Point-source antennaSecondary reflectorAny of the above

Calculate the beamwidth of a microwave dish antenna with a 6-m mouth diameter when used at 5 GHz.

  0.49°4.9°7°0.7°

Zoning refers to  A method of producing a radome

Changing a spherical wavefront into a plane waveCreating a polar radiation patternFading into nonreality

Which microwave oscillator has high gain, low-noise characteristics, and wide bandwidth?

  Traveling wave tube oscillatorGunn oscillatorKlystron oscillatorMagnetron oscillator

Which is not an advantage of the Gunn gallium arsenide oscillator?

  Ease of removing heat from the chipSmall sizeRuggednessLack of filamentsLow cost of manufacture

The i in p-i-n diode refers to  Indium

ImpactIntegratedIntrinsic

Which is not a typical application of a ferrite in a microwave system?

  attenuatoramplifierisolatorcirculator

A low-noise microwave amplifier that provides amplification via the variation of a reactance is known as a

  MaserLaserYigParametric amplifier

The major difference between a laser and a maser is the  Frequency of the signal being amplified

Amplitude of the signal being amplifiedBandwidth of the signal being amplifiedPhase of the signal being amplified

Lasers are useful in  Industrial welding

Surgical proceduresDistance measuringCompact disc playersAll the above

Which of the following semiconductors is not used as a microwave device?

   p-i-n diodeBaritt diodeZener diodeTunnel diode

Which of the following represent typical failure mode(s) for a TWT amplifier?

  Low gainSpurious modulationPoor frequency responseLow RF outputAll the above

Which of the following is not used as a microwave antenna?  Patch antenna

Marconi antennaLens antennaHorn antenna

Compared to linear power supplies, switching power supplies are

  Less efficientMore efficientSimplerHeavier

  42.4 cm2

424 m2

4.24 m2

424 cm2

MPORTANT PSU QUESTION(microwave,emt,communication)-part-3

Q101 THE MAXIMUM POWER THAT CAN BE HANDLED BY A FERRITE COMPONENT IS LIMITED BY (a)curie temperature (b)saturation magnetization (c)line width (d)gyromagnetic resonance ans-a

Q102 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 ans-d

Q103 A DUPLEXER IS USED (a)to couple two different antennas to a transmitter without mutual interference (b)to allow the one antenna to be used for reception or transmission without mutual interference (c)to prevent interference b/w two antennas when they are connected to a receiver (d)to increases the speed of the pulses in a pulsed radar ans-b

Q104 FOR SOME APPLICATION CIRCULAR WAVEGUIDE MAY BE PREFERRED OVER RECTANGULAR ONE BECAUSE OF (a)the smaller cross section needed at any frequency (b)lower attenuation (c)freedom from spurious modes (d)rotation of polarisation ans-b

Q105 INDICATE WHICH OF THE FOLLOWING CANNOT BE FOLLOWED BY THE WORD WAVEGUIDE (a)elliptical (b)flexible (c)coaxial (d)ridged ans-c

Q106 IN ORDER TO REDUCE CROSS SECTIONAL DIMENSIONS,THE WAVEGUIDE TO USE IS (a)circular

(b)ridged (c)rectangular (d)flexible ans-b

Q107 FOR LOW ATTENUATION BEST TRANSMISSION MEDIUM IS (a)flexible waveguide (b)ridged waveguide (c)rectangular waveguide (d)coaxial line ans-c

Q108 A MICROWAVE TUBE AMPLIFIER USES AN AXIAL MAGNETIC FIELD AND A RADIAL ELECTRIC FIELD .THIS IS A (a)reflex klystron (b)coaxial magnetron (c)travelling wave magnetron (d) cfa ans-d

Q109 ONE OF THE FOLLOWING IS UNLIKELY TO BE USED AS A PULSED DEVICE.IT IS A (a)multicavity klystron (b)bwo (c)cfa (d)twt ans-b

Q110 ONE OF THE REASON WHY VACCUM TUBES EVENTUALLY FAIL AT MICROWAVE FREQUENCIES IS THAT THEIR (a)nf increase (b)transit time become too short (c)shunt capacitive reactances become too large (d)series inductive reactances become too small ans-a

Q111 INDICATE THE FALSE STATEMENT .TRANSIT TIME IN MICROWAVE TUBE WILL BE REDUCED IF (a)the electrodes are brought together (b)a higher anode current is used (c)multiple or coaxial leads r used (d)the anode voltage is made large ans-c

Q112 THE MULTICAVITY KLYSTRON (a)is not a good low level amplifier because of noise (b)has a high repeller voltage to ensure a rapid transit time (c)is not suitable for pulsed operation (d)needs a long transit time through the buncher cavity to ensure current modulation ans-a

Q113 INDICATE THE FALSE STATEMENT.KLYSTRON AMPLIFIERS MAY USE INTERMEDIATE CAVITIES TO (a)prevent the oscillations that occurs in two cavity klystron (b)increase the bw (c)improve the power gain (d)increase the efficiency of the klystron ans-a

Q114 THE TWT IS SOMETIMES PREFERRED TO THE MULTICAVITY KLYSTRON AMPLIFIER ,BECAUSE THE FORMAR (a)is more efficient (b)has a greater bw (c)has a higher number of modes (d)produses a higher o/p power ans-b

Q115 THE TRANSIT TIME IN THR REPELLER SPACE OF A REFLEX KLYSTRON MUST BE N+3/4 CYCLE TO ENSURE THAT (a)electrons r accelerated by the gap voltage on their return (b)returning electrons gives energy to rhe gap oscillations (c)it is equal to the period of the cavity oscillations (d)the repeller is not damaged by stricking electrons ans-b

Q116 THE CAVITY MAGNETRON USE STRAPPING TO (a)prevent mode jumping (b)prevent cathod back heating (c)ensure bunching (d)improve the phase focusing ans-a

Q117 A MAGNETIC FIELD IS USED IN THE CAVITY MAGNETRON TO (a)prevent anode current in the absence of oscillations (b)ensure that the oscillations r pulsed (c)help in focusing the electron beam,thus preventing spreading (d)ensure that the electrones will orbit around the cathod

ans-d

Q118 TO AVOID DIFFICULTIES WITH STRAPPING AT HIGH FREQUENCYS,THE TYPE OF CAVITY STRUCTUER USED IN THE MAGNETRON IS THE (A)HOLE AND SLOT (b)slot (c)vane (d)rising sun ans-d

Q119 THE PRIMARY PURPOSE PF THE HELIX IN THE TWT IS (a)prevent the electron beam spreading in the long tube (b)reduce axial velocity of the rf field (c)ensure broadband operation (d)reduce the noise figure ans-b

Q120THE ATTENUATOR IN THE TWT IS USED FOR (a)help focusing (b)prevent oscillations (c)prevent saturatuion (d)increase gain ans-b

Q121 PERIODIC PERMANENT MAGNET FOCUSING IS USED WITH TWT TO (a)allow pulsed operation (b)improve electron bunching (c)avoid the bulk of an electromagnet (d)allow coupled cavity operation at the high frequency ans-c

Q122 THE TWT IS SOMETIMES PREFERRED TO THE MAGNETRON AS A RADAR TRANSMITTER O/P TUBE BECAUSE IT IS (a)capable of longer duty cycle (b)a more efficient amplifier (c)more broadband (d)less noise ans-a

Q123 A MAGNETRON WHOSE OSCILLATING FREQUENCY IS ELECTRONICALLY ADJUSTABLE OVER A WIDE RANGE IS CALLED (a)coaxial magnetron

(b)ditcher tuned magnetron (c)frequency agile magnetron (d)vtm ans-d

Q124 INDICATE WHICH OF THEE FOLLOWING IS NOT A TWTY SLOW WAVE STRUCTURE (a)periodic permanent magnet (b)coupled cavity (c)helix (d)ring bar ans-a

Q125 THE GLASS TUBE OF A TWT MAY BE COATED WITH AQUADAG TO (a)help focusing (b)provide attenuation (c)improve bunching (d)increse gain ans-b

Q126 A BACKWARD WAVE OSCILLATOR IS BASED ON THE (a)rising sun magnetron (b)cross field amplifier (c)coaxial magnetron (d)travelling wave tube ans-d

Q127 A PARAMATRIC AMPLIFIER MUST BE COOLED (a)because paramatric amplifications generates a lot of heat (b)to increase bw (c)because it cannot operate at room temp (d)to improve the noise performance ans-d

Q128 A RUBY MASER AMPLIFIER MUST BE COOLED (a)because maser amplifiers generats a lot of heat (b)to increase bw (c)because it can not operate at room temp (d)to improve the noise performance ans-c

Q129 THE TRANSMISSION SYSTEM USING TWO GROUND PLANES IS (a)microstrip

(b)elliptical waveguide (c)parallel wire line (d)stripline ans-d

Q130 INDICATE THE FALSE STATEMENT.AN ADVANTAGE OF USING STTRIPLINE OVER WAVVGUIDE IS its (a)smaller bulk (b)greater bw (c)higher power handling capability (d)greater compatibility with solid state device ans-c

Q131 INDICATE THE FALSE STATEMENT.AN ADVANTAGE OF USING STRIPLINE OVER MICROSTRIPLINE IS ITS (a)easier integration with semiconductor devices (b)lower tendency to radiate (c)higher isolation b/w ajacent ckts (d)higher q ans-a

Q132 SURFACE ACOUSTIC WAVE PROPAGATE IN (a)gallium arsenide (b)indium phosphste (c)stripline (d)quartz crystal ans-d

Q133 SAW DEVICES MAY BE USED AS (a)transmission media like stripline (b)filters (c)uhf amplifiers (d)oscillator at milimiter frequency ans-b

Q134 INDICATE THE FALSE STATEMENT.FET'S R PREFERRED TO BIPOLAR TRANSISTOR AT THE HIGHEST FREQUENCIES BECAUSE THEY ARE (a)less noisy (b)lend themselves more readily to integration (c)are capable of higher efficiencies (d)can provide higher gain ans-b

Q135 THE BIGGEST ADVANTAGE OF THE TRAPATT DIODE OVER THE IMPATT DIODE IS IT'S (a)lower noise (b)higher efficiency (c)ability to operate at higher frequency (d)lesser sensitivity to harmonics ans-b

Q136 INDICATE WHICH OF THE FOLLOWING DIODE WILL PRODUCE THE HIGHEST PULSED POWER O/P (a)varactor (b)gunn (c)schottky diode (d)rimpatt diode ans-d

Q137 INDICATE WHICH OF THE FOLLOWING DIODE DOES NOT USES -VE RESISTANCE IN IT'S OPERATION (a)backward (b)gunn (c)impatt (d)tunnel ans-a

Q138 ONE OF THE FOLLOWING IS NOT USED AS A MICROWAVE MIXER OR DETECTOR (a)crystal diode (b)schottky barrier diode (c)backward diode (d)pin diode ans-d

Q139 ONE OF THE FOLLOWING MICROWAVE DIODE IS SUITABLE FOR VERY LOW POWER OSCILLATOR ONLY (a)tunnel (b)avalanche (c)gunn (d)impatt ans-a

Q140 THE TRANSFERRED-ELECTRON BULK EFFECT OCCURS IN (a)germenium (b)gallium arsenide (c)silicon (d)metal semiconductor junctions ans-b

Q141 THE GAIN BW FREQUENCY OF A MICROWAVE TRANSISTOR,is THE FREQUENCY AT WHICH (a)alpha of the transistor falls by 3db (b)beta of the transistor falls by 3 db (c)power gain of the transistor falls to unity (d)beta of the transistor falls to unity ans-d

Q142 A VARACTOR DIODE MAY BE USEFUL AT MICROWAVE FREQUENCY(INDICATE THE FALSE STATEMENT) (A)for electronic tunning (b)for frequency multiplication (c)as an oscillator (d)as a paramatric amplifier ans-c

143 FOR A MICROWAVE TRANSISTOR TO OPERATE AT THE HIGHEST FREQUENCY(INDICATE THE FALSE STATEMENT) (a)collector voltage must be large (b)collector current must be large (c)base should be thin (d)emitter area must be large ans-d

Q144 IF HIGH ORDER FREQUENCY MULTIPLICATION IS REQUIRED FROM A DIODE MULTIPLIER (a)the resestive cutoff frequency must be high (b)a small value of base resistance is required (c)a step recovery diode must be used (d)a large range of capacitance variation is needed ans-c

Q145 TRAVELLING WAVE PARAMATRIC AMPLIFIER ARE USED TO (a)provide a greater gain (b)reduce the number of varactor diode required (c)avoid the need of coupling (d)provide a greater bw ans-d

Q146 A PARAMATRIC AMPLIFIER SOMETIMES USES A CIRCULATOR TO (a)prevent noise feedback (b)allow antenna to be used simultaneously for transmission and reception (c)seperate the signal and idler frequency

(d)permit more efficient pumping ans-a

Q147 THE NON DEGENERATED ONE PORT PARAMATRIC AMPLIFIER SHOULD HAVE A HIGH RATIO OF PUMP TO SIGNAL FREQUENC BECAUSE THIS (a)permits satisfactory high frequency operation (b)yields a low nf (c)reduces pump power required (d)permits satisfactory low frequency operation ans-b

Q148 THE TUNNEL DIODE (a)has a tiny hole through it's center to facilitate tunneling (b)ia a point contact diode with a very high reverse resistance (c)uses a high doping level to provide a narrow junction (d)works by quantam tunneling exhibited by gallium arsenide only ans-c

Q149 A TUNNEL DIODE IS LOSELY COUPLED TO IT'S CAVITY IN ORDER TO (a)increase the frequency stability (b)increase the available -ve resistance (c)faciliting tunning (d)allow operation at the high frequency ans-a

Q150 THE -VE RESISTANCE IN A TUNNEL DIODE (a)is amximum at the peak point of the characteristics (b)is available b/w peak n vally point (c)is maximum at valley point (d)may be improved by use of reverse bias ans-b

The correct answer for each question is indicated by a .

The microstrip lines shown in the circuit above are used for

A)low-noise amplification

B) decoupling to prevent feedback

C)impedance matching and tuning

D)signal coupling

Small wire loop inductors and capacitors are used to provide

A)low-noise amplification

B) decoupling to prevent feedback

C)impedance matching and tuning

D)signal coupling

Hollow metal conducting pipes designed to carry and constrain the electromagnetic waves of a microwave signal are

A)wavetraps

B) waveguides

C)traveling wave tubes

D)microwave tubes

A microwave component which is used to interconnect two sections of waveguide is the

A)T section

B) curved section

C)choke joint

D)tapered wedge

A waveguidelike device that acts as a high-Q parallel resonant circuit is a

A)microstrip

B) klystron

C)horn

D)cavity resonator

A three-port microwave device used for coupling energy in only one direction around a closed loop is a

A)circulator

B) joint

C)terminator

D)cavity resonator

Which of the following diodes is not typically used in the microwave region?

A)point-contact

B) standard PN

C)Schottky

D)hot carrier

Which of the following diodes does not oscillate due to negative-resistance characteristics?

A)tunnel

B) SCR

C)Gunn

D)IMPATT

A thin piece of N-type gallium arsenide or indium phosphide semiconductor which forms a special resistor when voltage is applied to it is the

A)tunnel diode

B) PIN diode

C)Gunn diode

D)varactor diode

A microwave vacuum tube using cavity resonators to produce velocity modulation of an electron beam which produces amplification is

A)a klystron

B) magnetron

C)a cathode-ray tube

D)traveling-wave tube