DUET 2021 Question Paper M.Tech Microwave Electronics

DU MTech Microwave Electronics
Topic:‐ ME MTECH

1) Using Newton‐ Raphson method, a root correct to three decimal places of the equation is

[Question ID = 10688]
1. 2.275

[Option ID = 42749]
2. 2.279

[Option ID = 42750]
3. 2.222

[Option ID = 42751]
4. None of the above

[Option ID = 42752]

2)
An eigen vector of P= is

[Question ID = 10689]
1.

[Option ID = 42753]
2.

[Option ID = 42754]
3.

[Option ID = 42755]
4.

[Option ID = 42756]

3)

[Question ID = 10690]
1.

[Option ID = 42757]

2.

[Option ID = 42758]

3.

[Option ID = 42759]

4.

[Option ID = 42760]

4)

[Question ID = 10691]
1.

[Option ID = 42761]
2.

[Option ID = 42762]
3.

[Option ID = 42763]
4.

[Option ID = 42764]

5) The value of given definite integral

is

[Question ID = 10692]
1. 1

[Option ID = 42765]
2. 0

[Option ID = 42766]
3. infinity

[Option ID = 42767]
4. ‐1

[Option ID = 42768]

6)

[Question ID = 10693]
1.

[Option ID = 42769]
2.

[Option ID = 42770]
3.

[Option ID = 42771]
4.

[Option ID = 42772]

7) The partial differentiation equation can be classified as

[Question ID = 10694]
1. Elliptic

[Option ID = 42773]
2. Parabolic

[Option ID = 42774]
3. Hyperbolic

[Option ID = 42775]
4. None of the above

[Option ID = 42776]

8)

[Question ID = 10695]
1.

[Option ID = 42777]
2.

[Option ID = 42778]
3.

[Option ID = 42779]
4.

[Option ID = 42780]

9)
​

[Question ID = 10696]
1.

[Option ID = 42781]
2.

[Option ID = 42782]
3.

[Option ID = 42783]
4.

[Option ID = 42784]

10) Match List I with List II

List I List II

Quantities Units

A. R/L I. Second

B. 1/LC II. Ohm

C. RC III. (Radian/Second)2

D. IV. (Second)‐1

Choose the correct answer from the options given below:

[Question ID = 10697]
1. A ‐ IV, B ‐ III, C ‐ I, D ‐ II

[Option ID = 42785]
2. A ‐ III, B ‐ IV, C ‐ II, D ‐ I

[Option ID = 42786]
3. A ‐ IV, B ‐ III, C ‐ II, D ‐ I

[Option ID = 42787]
4. A ‐ III, B ‐ IV, C ‐ I, D ‐ II

[Option ID = 42788]

11) For the circuit given below, what is the expression for the voltage V?

[Question ID = 10698]
1.

[Option ID = 42789]
2.

[Option ID = 42790]

3.

[Option ID = 42791]

4.

[Option ID = 42792]

12) It is required to find the current through a particular branch of a linear bilateral network without mutual coupling when
the branch impedance takes four different values. Which one of the following methods will be preferred?[Question ID =
10699]
1. Superposition theorem [Option ID = 42793]
2. Thevenin’s equivalent circuit [Option ID = 42794]
3. Mesh Analysis [Option ID = 42795]
4. Nodal analysis [Option ID = 42796]

13) A two port network is characterized by

I1 = 3 V1 + 4 V2

6 I2 = 2 V1 – 4 V2

The A, B, C, D parameters for this network are

[Question ID = 10700]
1. 2, ‐3, 10, ‐9

[Option ID = 42797]
2. 2, 3, 6, 9

[Option ID = 42798]
3. 3, 2, ‐9, 6

[Option ID = 42799]
4. 3, ‐2, 9, ‐6

[Option ID = 42800]

14) In the delta equivalent of the below star connected circuit, ZQR is equal to

[Question ID = 10701]
1. 5 Ω

[Option ID = 42801]
2. (10 + j30) Ω

[Option ID = 42802]
3. 40 Ω

[Option ID = 42803]
4. (20 + j10) Ω

[Option ID = 42804]

15) Which one of the following impedance values of load will cause maximum power to be transferred to the load for the
network shown in the figure?

[Question ID = 10702]
1. 2 Ω

[Option ID = 42805]
2. – j2 Ω

[Option ID = 42806]
3. (2 + 2j) Ω

[Option ID = 42807]
4. (2 – 2j) Ω

[Option ID = 42808]

16) Integrated Circuit based computers are started from which generation?[Question ID = 10703]
1. 3r d generation [Option ID = 42809]
2. 2nd generation [Option ID = 42810]
3. 1st generation [Option ID = 42811]
4. 4th generation [Option ID = 42812]

17) Which operating system doesn’t support networking between computers?[Question ID = 10704]
1. Windows NT [Option ID = 42813]
2. Windows 2000 [Option ID = 42814]
3. Windows 95 [Option ID = 42815]
4. Windows 3.1 [Option ID = 42816]

18) In C language, what is the output of the following code

<#include<studio.h>

void f()

{

static int i;

++i;

printf("%d", i);

}

int main()

{

f();

f();

f();

f();

}

[Question ID = 10705]
1. 1111

[Option ID = 42817]
2. 0000

[Option ID = 42818]
3. Error

[Option ID = 42819]
4. 1234

[Option ID = 42820]

19) What will be the output of the following C code?

#include<studio.h>

int main()

{

int c = 2 ^ 4;

printf("%d\n", c);

}

[Question ID = 10706]
1. error

[Option ID = 42821]
2. 4

[Option ID = 42822]
3. 6

[Option ID = 42823]
4. 0

[Option ID = 42824]

20) The number of digits required to represent a decimal number 31 in equivalent binary form are[Question ID = 10707]
1. 5 [Option ID = 42825]
2. 6 [Option ID = 42826]
3. 4 [Option ID = 42827]
4. 7 [Option ID = 42828]

21) The value of by the using one‐segment trapezoidal rule is most nearly

[Question ID = 10708]
1. 1.707

[Option ID = 42829]
2. 2.707

[Option ID = 42830]
3. 7.807

[Option ID = 42831]
4. 4.672

[Option ID = 42832]

22) If the ratio of the concentration of electrons to that of holes in a semiconductor is 7/5 and the ratio of currents is 7/4,
then what is the ratio of their drift velocities?[Question ID = 10709]
1. 4/7 [Option ID = 42833]
2. 5/4 [Option ID = 42834]
3. 5/8 [Option ID = 42835]
4. 4/5 [Option ID = 42836]

23) The circuit has two oppositely connected ideal diodes in parallel. What is the current flowing in the circuit?

[Question ID = 10710]
1. 1.33 A [Option ID = 42837]
2. 2 A [Option ID = 42838]
3. 2.31 A [Option ID = 42839]
4. 1.71 A [Option ID = 42840]

24) The carrier mobility in a semiconductor is 0.4 m2/V s. Its diffusion constant at 300 K will be (in m2 / s)[Question ID =
10711]
1. 0.01 [Option ID = 42841]
2. 0.43 [Option ID = 42842]
3. 0.04 [Option ID = 42843]
4. 0.16 [Option ID = 42844]

25) A one‐sided abrupt junction has 1021 /m3 of dopants on the lightly doped side, zero bias voltage and a built in potential
of 0.2 V. The depletion width of the abrupt junction is approximately

(q = 1.6 x 10 ‐19 C, Ɛ r = 16 and Ɛ o = 8.875 x 10‐12 F/m)

[Question ID = 10712]
1. 0.6 μm

[Option ID = 42845]
2. 3 μm

[Option ID = 42846]
3. 0.036 μm

[Option ID = 42847]
4. 1.5 μm

[Option ID = 42848]

26) The Hall‐ coefficient of a specimen of doped semiconductor is 3.06 x 10‐4 m3 C‐1 and the resistivity of the specimen is
6.93 x 10‐3 Ωm. the majority carrier mobility will be:

[Question ID = 10713]
1. 0.0442 m2 / V‐sec

[Option ID = 42849]
2. 0.024 m2 / V‐sec

[Option ID = 42850]
3. 0.034 m2 / V‐sec

[Option ID = 42851]
4. 0.0625 m2 / V‐sec

[Option ID = 42852]

27) A schottky diode clamp is used along with switching BJT for[Question ID = 10714]
1. Reducing power dissipation [Option ID = 42853]
2. Increasing the value of current gain [Option ID = 42854]
3. Reducing switching time [Option ID = 42855]
4. Reducing the base current [Option ID = 42856]

28) If a p‐n junction has doping densities Na = 3.5 × 1018 cm–3 and Nd = 2.5 × 1015 cm–3 in the two regions then its built‐in
potential at 300 K is _____________. (Take ni = 2.5 × 1010 cm–3)[Question ID = 10715]
1. 0.393 V [Option ID = 42857]
2. 1.574 V [Option ID = 42858]
3. 0.787 V [Option ID = 42859]
4. 0 V [Option ID = 42860]

29) If a GaAs IMPATT diode has drift length of 3 µm and a carrier drift velocity of 1.5 × 107 cm/s then the drift time of the
carrier and the operating frequency for this IMPATT diode are ___________ and _____ respectively.[Question ID = 10716]
1. 4 × 10‐9 s and 50 GHz [Option ID = 42861]
2. 2 × 10‐6 s and 100 GHz [Option ID = 42862]
3. 2 × 10‐11 s and 25 GHz [Option ID = 42863]
4. 1 × 10‐10 s and 100 GHz [Option ID = 42864]

30) A 4 GHz carrier is DSB‐SC modulated by a lowpass message signal with maximum frequency of 2MHz. The resultant
signal is to be ideally sampled. The minimum frequency of the sampling impulse train should be[Question ID = 10717]
1. 8.004 GHz [Option ID = 42865]
2. 8 MHz [Option ID = 42866]
3. 4 MHz [Option ID = 42867]
4. 8 GHz [Option ID = 42868]

31) A 10MHz carrier is frequency modulated by a sinusoidal signal of 500 Hz, the maximum frequency deviation being 50
kHz. The bandwidth required, as given by Carson’s rule is[Question ID = 10718]
1. 100kHz [Option ID = 42869]
2. 99kHz [Option ID = 42870]
3. 101kHz [Option ID = 42871]
4. 98kHz [Option ID = 42872]

32) The bit stream 01001 is differentially encoded using ‘Delay and Ex‐OR’ scheme for DPSK transmission. Assuming the
reference bit as a ‘1’and assigning phases of ‘0’and ‘π’for 1’s and 0’s respectively, in the encoded sequence, the
transmitted phase sequence becomes

[Question ID = 10719]
1. π π 0 π π

[Option ID = 42873]
2. 0 π π π 0

[Option ID = 42874]
3. 0 0 π π 0

[Option ID = 42875]
4. π 0 π π 0

[Option ID = 42876]

33) A source generates three symbols with probabilities 0.25, 0.25 and 0.50 at a rate of 3000 symbols per second.
Assuming independent generation of symbols, the most efficient source encoder would have average bit rate is[Question ID
= 10720]
1. 6000 bits/sec [Option ID = 42877]
2. 1500 bits/sec [Option ID = 42878]
3. 4500 bits/sec [Option ID = 42879]
4. 3000 bits/sec [Option ID = 42880]

34) A superheterodyne receiver operates in the frequency range of 58 MHz – 68 MHz. The intermediate frequency fIF and
local oscillator frequency fLO are chosen such that fIF ≤ fLO. It is required that the image frequencies fall outside the 58
MHz – 68 MHz band. The minimum required fIF (in MHz) is[Question ID = 10721]
1. 5 MHz [Option ID = 42881]
2. 10 MHz [Option ID = 42882]
3. 15 MHz [Option ID = 42883]
4. 1 MHz [Option ID = 42884]

35) Coherent demodulation of FSK signal can be detected using[Question ID = 10722]
1. Bandpass filters and envelope detectors [Option ID = 42885]
2. Matched filter [Option ID = 42886]
3. Correlation receiver [Option ID = 42887]
4. Discriminator detection [Option ID = 42888]

36) Consider sinusoidal modulation in an AM systems. Assuming no over modulation , the modulation index (µ) when the
maximum and minimum values of the envelope, respectively, are 4V and 2V is[Question ID = 10723]
1. 0.33 [Option ID = 42889]
2. 0.22 [Option ID = 42890]
3. 0.11 [Option ID = 42891]
4. 0.7 [Option ID = 42892]

37) The Nyquist sampling rate for the signal is given by

[Question ID = 10724]
1. 140 Hz

[Option ID = 42893]
2. 100 Hz

[Option ID = 42894]
3. 120 Hz

[Option ID = 42895]
4. 50 Hz

[Option ID = 42896]

38) The divergence of the vector A = is

[Question ID = 10725]
1.

[Option ID = 42897]
2.

[Option ID = 42898]
3.

[Option ID = 42899]
4.

[Option ID = 42900]

39) If Electric flux density , the volume charge density at (‐1, 0, 2) is

[Question ID = 10726]
1.

[Option ID = 42901]
2.

[Option ID = 42902]
3.

[Option ID = 42903]
4.

[Option ID = 42904]

40) Two point charges ‐4 µC and 4 µC are located at (2, ‐2, 3) and (1, 4, 1), respectively. Assuming zero potential at
infinity, the potential at (1, 0, 1) is[Question ID = 10727]
1. ‐3 kV [Option ID = 42905]
2. ‐1 kV [Option ID = 42906]
3. ‐2 kV [Option ID = 42907]
4. ‐4 kV [Option ID = 42908]

41) Voltage applied across a dielectric produces an electrostatic 50 times greater than air. The dielectric constant of the
dielectric will be[Question ID = 10728]
1. 5 [Option ID = 42909]
2. 10 [Option ID = 42910]
3. 20 [Option ID = 42911]
4. 50 [Option ID = 42912]

42) The electric field intensity in Styrofoam ( = 1.03) filing the space between the plates of parallel‐plate capacitor is 20
KV/m. The distance between the plates is 1.7 mm. Electric flux density D and the potential difference between the plates
are respectively:

[Question ID = 10729]
1. 177 nC/m2 and 30 V

[Option ID = 42913]
2. 177 nC/m2 and 17 V

[Option ID = 42914]
3. 182.31 nC/m2 and 17 V

[Option ID = 42915]
4. 182.31 nC/m2 and 34 V

[Option ID = 42916]

43) A lossless transmission line of length 15 cm with L = 20μH/m, C = 45pF/m is opearated at 250 MHz. Its electrical length
is

[Question ID = 10730]
1. π

[Option ID = 42917]
2. 2.25π

[Option ID = 42918]
3. 2.57λ

[Option ID = 42919]
4. 0.25λ

[Option ID = 42920]

44) The input impedance of a transmission line of length l < λ/4 and open circuited at the far end is

[Question ID = 10731]
1. resonative

[Option ID = 42921]
2. capacitive

[Option ID = 42922]
3. inductive

[Option ID = 42923]
4. resistive

[Option ID = 42924]

45) A lossless line of 50 Ω is terminated in a load of 100 Ω resistive. The VSWR of this line is

[Question ID = 10732]
1. 1:4

[Option ID = 42925]
2. 2:1

[Option ID = 42926]
3. 1:2

[Option ID = 42927]
4. 4:1

[Option ID = 42928]

46) The propagation constant of a transmission line with impedance and admittance of 9 and 16 respectively is[Question ID
= 10733]
1. 225 [Option ID = 42929]
2. 12 [Option ID = 42930]
3. 25 [Option ID = 42931]
4. 144 [Option ID = 42932]

47) Normalized impedance of 0.3 + j0.4 lies in the[Question ID = 10734]
1. Lower half of the impedance smith chart. [Option ID = 42933]
2. Horizontal line of the chart. [Option ID = 42934]
3. Upper half of the impedance smith chart. [Option ID = 42935]
4. Vertical line of the chart. [Option ID = 42936]

48) A commonly used antenna for TV reception is[Question ID = 10735]
1. Log periodic antenna [Option ID = 42937]
2. Simple dipole antenna [Option ID = 42938]
3. Yagi antenna [Option ID = 42939]
4. Horn antenna [Option ID = 42940]

49) A reflex Klystron function as:[Question ID = 10736]
1. Microwave amplifier. [Option ID = 42941]
2. A high gain cavity. [Option ID = 42942]
3. Both as Microwave amplifier and oscillator. [Option ID = 42943]
4. Microwave oscillator. [Option ID = 42944]

50) Radiation resistance of a current element of length dl is

[Question ID = 10737]
1. ohms

[Option ID = 42945]

2. ohms

[Option ID = 42946]
3. ohms

[Option ID = 42947]

4. ohms

[Option ID = 42948]