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 resonanceans-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 switchans-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 radarans-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 polarisationans-b

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

IN ORDER TO REDUCE CROSS SECTIONAL DIMENSIONS,THE WAVEGUIDE TO USE IS(a)circular(b)ridged(c)rectangular(d)flexibleans-b

Q107 FOR LOW ATTENUATION BEST TRANSMISSION MEDIUM IS(a)flexible waveguide(b)ridged waveguide(c)rectangular waveguide(d)coaxial lineans-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) cfaans-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)twtans-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 smallans-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 largeans-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 modulationans-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 klystronans-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 powerans-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 electronsans-b

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

Q120THE ATTENUATOR IN THE TWT IS USED FOR(a)help focusing(b)prevent oscillations(c)prevent saturatuion(d)increase gainans-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 frequencyans-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 noiseans-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)vtmans-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 barans-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 gainans-b

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

Q129 THE TRANSMISSION SYSTEM USING TWO GROUND PLANES IS(a)microstrip(b)elliptical waveguide(c)parallel wire line(d)striplineans-d

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

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

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

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

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

Q140 THE TRANSFERRED-ELECTRON BULK EFFECT OCCURS IN(a)germenium(b)gallium arsenide(c)silicon(d)metal semiconductor junctionsans-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 unityans-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 amplifierans-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 largeans-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 neededans-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 bwans-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 pumpingans-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 operationans-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 onlyans-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 frequencyans-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 biasans-bMultiple Choice Questions 1 Solution at the bottom1. The Wavelengthcorrespondto Microwave frequency range isa. 30 to 300GHzb. 3 to 30 GHzc. 0.3 to 3 Ghzd. 300 to 3oooGHz

2.The main advantage of microwave is that-a. Highly Directive.b.Moves at the speed of light.c.S/N ratio grater.d. Highpenetrationpower.

3.Reflex Klystron is a -a.Ampilfier.b.Oscillator.c.Attenuator.d.Filter.

4.Klystron operates on the principle of-a. Amplitude Modulation.b.Frequency Modulation.c.Pulse Modulation.d.Velocity modulation.

5.In multicavity Klystron additional cavities are inserted betweenbuncher and catchercavitiesto achieve-a.Higher Gainb.HigherEfficiencyc.Higher Frequencyd.Higher Bandwidth

6.The modes in the reflex Klystron -a. give same frequency butdifferenttransit time.b.are caused by spurious frequency modulation.c.are just for theoretical consideration.d.result fromexcessive transit time across resonator gap.

7.A reflex Klystron function asa. MicrowaveOscillator.b.Amplifierc.Phase shifterd.Both amplifier and phase shifter

8.A space between two cavities in two cavity klystron isa.Drift spaceb.Free spacec.Running apced.Normal space

9. Magnetron is ana. Amplifierb.Oscillatorc. Phase shifterd.Both phase shifter and amplifier

10.TWT isa.Oscillatorb.TunedAmplifierc.Wide bandAmplifier.d.Bothamplifierand OscillatorSolution1.b, 2.a, 3.b, 4.d, 5.a, 6.a, 7.a, 8.a, 9.b, 10.cDirections: The following questions consist of two statements, one labelled the Assertion A and the other labelled the Reason R. You are to examine these two statements carefully and decide f the Assertion A and the Reason R are individually true and f so, whether the Reason is a correct explanation of the Assertion. Select your answers to these items using the codes given below and mark your answer sheet accordingly.Codes:(a) Both A and R are true and R is the correct explanation of A(b) both A and R are true but R Is NOT a correct explanation of A(c) A is true but R is false(d) A is false but R is true8. Assertion (A): By superimposing the log magnitude versus phase angle plot of open-loop transfer function on Nichols chart, it is possible to determine the closed-loop frequency response of the system.Reason (R): Nichols chart gives constant M and N loci in the gain-phase plane.Ans:-A9. Assertion (A): A communication satellite is a microwave link repeater.Reason (R): A communication satellite receives the signal beamed up by an earth station. It amplifies this signal and retransmits it to ground station.Ans:-B10. Assertion (A): FM systems exhibit threshold.Reason (R): Noise affects the instantaneous frequency in a non-linear fashion.Ans:-B11. The mean square value of the shot noise current(a) Varies inversely as average current(b) is independent of average current(c) Varies as ?average current(d) Varies directly as average currentAns:- D12. Consider the following features regarding satellite communication:1. Height of Satellite2: Downlink frequency3. Gain of transmitting antenna4. Gain of receiving antennaThe free space transmission loss depends on(a) 1 and 3(b) l and 2(c) 2 and 3(d) 3 and 4Ans:-B13. In a Mesh topology of communication network, if there are N stations, the total number of possible full duplex links is(a) N1(b) N (N1)(c) N (N1) / 2(d) (N-1) / 2Ans:-D14. Values of VSWR measured by terminating the load end of a transmission line first with horn, then with a short and finally with a matched load, will be respectively(a) 20, 1.9 and 1.01(c) 1.9, 1.01 and 20(b) 20, 1.01 and 1.9(a) 1.9, 2O and 1.01Ans:-D15. In an 8085 microprocessor, the accumulator contents get altered by the instruction(a) ANI 5C(b) CMP C(c) CPI 3A(d) ORA AAns:- D16. The maximum value of mutual Inductance of two inductively coupled coils with self inductance L1 = 49 mH and L 2 = 81 mH is(a) 130 mH(b) 63 mH(c) 32 mH(d) 3969 mHAns:-B17 . The resonant frequency of a series RLC circuit is 1.5 MHz with the resonating capacitor set at l50 pF. If the bandwidth is 10 kHz, then the effective resistance of the circuit in Ohms would be approximately(a) 29.5(b) 14.75(c) 9.4(d) 4.7 Ans:-B18. The system y (t) = tx (t) + 4 is(a) Non-linear, time-varying and unstable(b) Linear, time-varying and unstable(c) Non-linear, time-invariant and unstable(d) Non-linear, time-varying and stableAns:-A19. A signal of bandwidth 4 kHz is recorded in a tape recorder at normal speed. If for transmission purposes, the recorder is replayed at 4 times the normal speed, then the transmission bandwidth will be(a) 16 kHz(b) 8 kHz(c) 4 kHz(d) 1 kHzAns:-A20. In LED, light is emitted because(a) Recombination of charge carriers takes place(b) Diode gets heated up(c) Light falling on the diode gets amplified(d) Light gets reflected due to lens actionAns:-A21. The gain of a negative feedback amplifier is 40 dB. If the attenuation of the feedback path is 50 dB, then the gain of the amplifier without feedback is(a) 78.92(b) 146.32(c) 215.51(d) 317.23Ans:-B22. The following table provides a comparison of the performances of common base (CB), common emitter (CE) and common collector (CC) configurations of a transistor:Parameter CB CE CC1. Input impedance low medium high2. Current gain high low high3. Voltage gain >1 >1