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Test Booklet Series

TEST BOOKLET

Electronics & Communication Paper

Topic Test – E.M. Theory & Microwave

Time Allowed: One Hour

Maximum Marks: 100

INSTRUCTIONS

1. IMMEDIATELY AFTER THE COMMENCEMENT OF THE EXAMINATION YOU SHOULD

CHECK THAT THIS TEST BOOKLET DOES NOT HAVE ANY UNPRINTED OR TORN OR

MISSING PAGES OR ITEMS ETC. IF SO, GET IT REPLACED BY A COMPLETE TEST

BOOKLET.

2. ENCODE CLEARLY THE TEST BOOKLET SERIES A, B, C, OR D AS THE CASE MAY BE IN

THE APPROPRIATE PLACE IN THE ANSWER SHEET.

3. You have to enter your Roll Number on the

Test Booklet in the Box provided alongside.

DO NOT write anything else on the Test Booklet.

4. This Test Booklet contains 60 items (questions). Each item comprises four responses (answers). You

will select the response which you want to mark on the Answer Sheet. In case you feel that there is

more than one correct response, mark the response which you consider the best. In any case, choose

ONLY ONE response for each item.

5. You have to mark all you responses ONLY on the separate Answer Sheet provided. See directions in

the Answer Sheet.

6. All items carry equal marks.

7. Before you proceed to mark in the Answer Sheet the response to various items in the Test Booklet,

you have to fill in some particulars in the Answer Sheet as per instructions sent to you with your

Admission Certificate.

8. After you have completed filling in all your responses on the Answer Sheet and the examination has

concluded, you should hand over to the Invigilator only the Answer Sheet. You are permitted to take

away with you the Test Booklet.

9. Sheets for rough work are appended in the Test Booklet at the end.

10. Penalty for wrong answers:

THERE WILL BE PENALTY FOR WRONG ANSWERS MARKED BY A CANDIDATE IN THE

OBJECTIVE TYPE QUESTION PAPERS.

(i) There are four alternatives for the answer to every question. For each question for which a

wrong answer has been given by the candidate, one-third (0.33) of the marks assigned to that

question will be deducted as penalty.

(ii) If a candidate gives more than one answer, it will be treated as a wrong answer even if one

of the given answers happens to be correct and there will be same penalty as above to that

question.

(iii) If a question is left blank, i.e., no answer is given by the candidate, there will be no penalty

for that question

DO NOT OPEN THIS TEST BOOKLET UNTIL YOU ARE ASKED TO DO SO


1A

Y

X

Z

1A

1. Consider the following statements about ‘Del’ operator:

1. It is a vector space function

2. It is a vector differential operator

3. It is vector quantity

Which of the following are correct statements:

(A) 1 & 2 only (B) 2 & 3 only (C) 1 & 3 only (D) 1, 2 & 3 only

2. Consider the following statements about various mathematical functions:

1. Gradient represents maximum space rate increase of scalar in magnitude only

2. Divergence is the net outward flux emanating per unit volume as the volume sinks to a point

3. Curl deals with rotation of a vector



3. Which of the statement is not correct:

(A) Divergence theorem changes closed surface integral to volume integral

(B) Divergence theorem is valid to any volume which is bounded by surface S

(C) Stoke’s theorem changes open surface integral to line integral over the closed curve

(D) Stoke’s theorem changes closed surface integral to line integral over the closed curve

4. An electric field on a plane is described by its potential V = 20 (r-3

) where r is the distance from the

source. The field is due to:

(A) monopole (B) dipole (C) both monopole& dipole (D) a quadruple

5. A charge of 1 Coulomb is placed near a grounded conducting plane at a distance of 0.25 meter. What

is the value of force between them?

0

0 0 0

1 1 1( ) ( ) ( ) ( )4

4 16A N B N C N D N

6. In the infinite plane x=6 meter there exists a uniform charge density of 21/

300C m

. What is the

value of associated electric field strength at origin due to this plane:

(A) 30 i V/m (B) 60 j V/m (C) 60 i V/m (D) 15 i V/m

7. Two infinitely long wires carrying current are as shown in the figure below. One wire is in the y-z

plane and parallel to the y-axis. The other wise is in the x-y plane and parallel to the x-axis.

Which components of the resulting magnetic field are non-zero at the origin?

(A) x, y, z components

(B) x, y components

(C) y, z components

(D) x, z components


8. Current density J in cylindrical coordinate system is given as

0 2

( , , ) 0 0

z

J r z for r a

rJ a for a r b

a

Where za is the unit vector along z direction axis. In the region for a r b what is the expression

for the magnetic field intensity vector H .

2 2 3 3 3 3 3 30 0 0 0

2 2 2( ) ( ) ( ) ( ) ( ) ( ) ( ) ( )

3 2

J J J JA r a B r a C r a D r a

r r a r r

9. Which of the following statement is not true about Magnetic field?

(A) For a Magnetic flux density B the total magnetic flux passing through a closed surface is always

equal to zero.

(B) For a magneto static field . 0lH dl or 0H

(C) . 0B Condition means magnetic poles can’t be isolated

(D) If B is the magnetic field and A is the magnetic vector potential then B A

10. Which of the following is the correct form of Laplacian operator for a vector:

(A) 2 ( . ) ( )V V V (B) 2V V

(C) 2 ( . ) ( )V V V (D) 2 .V V

11. If the potential functions V1 and V2 satisfy Laplace’s equation within a closed region and assume the

same values on its surface, then which of the following is correct ?

(A) V1 and V2 are identical (B) V1 is inversely proportional to V2

(C) V1 has the same direction as V2 (D) V1 has the same magnitude as V2 but has different direction

12. Current in electric field is analogous to which parameter in magnetic field:

(A) MMF (B) Reluctance (C) Flux (D) Conductance

13. If the dielectric constant is expressed as complex quantity ' ''j then total capacitor current is

expressed as:

(A) '' '( )totalJ w E jw E (B) '' '( )totalJ w E jw E

(C) ' ''( )totalJ w E jw E (D) ' ''( )totalJ w E jw E

14. For a travelling wave in +X direction Value of E is that it has only Ey in +Y direction then wave

equation in Ey is:

(A)

2 2

y y

2 2

E E

y t

(B)

2 2

y y

2 2

E E

x t

(C)

22yx

2 2

EE

y t

(D)

2 2

y y

2 2

E E

t x

15. If electric Field E 0.1te txa

and = 40 then displacement current crossing an area of 0.1m

2 at t =

0, will be

(A) 0 (B) 0.04 0 (C) 0.4 0 (D) 4 0


16. If electric field components of 2, different uniform plane wave are :

Wave 1 : ( )

0( ) j t y

x zE E a ja e

Wave 2 : ( )

0 ( ) j t z

x yE E a a e

then which of the following statements are true about polarization of wave 1 & wave 2

(A) Wave 1 - Linear, wave 2 – Right hand Circular

(B) Wave 1 - Linear, Wave 2 – Left Hand circular

(C) Wave 1 – Right hand Circular, Wave 2 - Linear

(D) Wave 1 – Left Hand Circular, Wave 2 - Linear

17. The waveguide (a = 1.5 cm, b = 1 cm) is loaded with a dielectric (εr = 4).which one of the following

is correct? The 8 GHz signal will:

(A) Pass through the waveguide (B) not pass through the waveguide

(C) Be absorbed in the guide (D) none of the above

18. .s

E H dS in Poynting theorem indicates:

(A) Electric and Magnetic fields are perpendicular to each other.

(B) Energy is transported in space by E and H field

(C) Energy is decreasing while advancing in space.

(D) The loss of energy is being made up by energy flowing into volume.

19. The input current in a matched transmission line is 50 mA and the load current is 1 mA. The line is 1

km long. The total attenuation N in the line is given by

(A) loge 50 (B) 50 dB (C) log10 50 nepers (D) 50 db

20. In an isotropic inharmonious dielectric medium free of charges and currents the wave equation for

the electric field having harmonic time independence of exp( )iwt is given by 2 2k w

(A) 2 2( . ) 0E E k E (B) 2 2( . ) 0E E k E

(C) 2 2( ) 0E E k E

(D) 2 2 0E E k E

21. The x-directed electric field Ex having sinusoidal time variation ejωt

and space variation in z-direction

satisfies the equation 2 2 0x xE k E under source free condition in a lossless medium.

What is the solution representing propagation in positive z-direction?

(A) Ex = E0 e–kz

(B) Ex = E0 e+jkz

(C) Ex = E0 e–jkz

(D) Ex = E0 e+kz

22.

A plane wave is generated under water o o81 and . The wave is parallel polarized. At the

interface between water and air, the angle for which there is no reflection is


(A) 83.88º (B) 83.66º (C) 84.86º (D) 84.08º

23. For a good conducting medium what are the values of intrinsic impedance angle and loss tangent:

(A) 90º, 45º (B) 45º,∞ (C) 90º,∞ (D) 90º, 90º

24. Consider the following powers related to Poynting vector:

1. 1

2aveP E H 2.

1

2ComplexP E H

3. 1

2InstP E H 4. InstP E H

Which of the following power/s formula is/are correct:

(A) 1 & 4 (B) 2 & 4 (C) 1, 2 & 4 (D) only 4

25. A plane wave of wavelength is traveling in a direction making an angle 60º with positive x-axis

and 90º with positive y-axis. The E field of the plane wave can be represented as (E0 is a constant)

(A)

3

0ˆ

j t x z

E yE e

(B)

3

0ˆ

j t x z

E yE e

(C)

3

0ˆ

j t x z

E yE e

(D)

3

0ˆ

j t x z

E yE e

26. For static and magnetic field in an inhomogeneous source-free medium which of the following

represents the correct form of two of Maxwell’s equations?

(A) .E = 0 ×B = 0 (B) .E = 0 .B = 0

(C) ×E = 0 ×B = 0 (D) ×E = 0 .B = 0

27. Magnetic current consists of:

(A) Entirely a displacement component and no conduction component.

(B) Entirely a conduction component and no displacement component.

(C) Due to both conduction component and displacement component

(D) None

28. Consider a parallel plate capacitor being charged. Consider the following statements:

1. Energy stored in the capacitor does not enter it through the connecting wires but through the

space around the wires and plates of capacitor.

2. Rate at which energy flows into this volume is equal to the integration of the Poynting vector

over the boundary of the volume between the plates

3. The Poynting vector points everywhere radially outward of the volume between the plates

4 The Poynting vector points everywhere radially into the volume between the plates

(A) 1, 2 & 3 only (B) 2, 3 & 4 only (C) 1, 2 & 4 only (D) 1, 3 & 4 only

29. A manufacturer produces a ferrite material with 0750 & 05 and 610 S/ m at 10 MHz at

this frequency material will behave like:

(A) Perfect dielectric& lossless (B) Perfect conducting &lossy

(C) Conducting& lossy (D) Dielectric& lossless


30. A lossless transmission line is connected to two identical voltage sources as shown in the figure. The

impedance measured at the midpoint 'AA of the line is:

Here characteristic impedance of transmission line is 100 Ω and length of transmission line is equal

to :

(A) ∞ (B) 100 (C) 50 (D) 25

31. A quarter wave transformer made of air filled coaxial cable matches two lines of 100 ohm and 36

ohm character impedance. The inner conductor of line is 10 mm in diameter then diameter of outer

conductor is:

(A) 1.6 mm (B) 13.6 mm (C) 27.2 mm (D) 32.5 mm

32. A 24 volt battery with 100 ohm source resistance is connected to a coaxial cable of characteristic

impedance of 50 ohm and is terminated by a load impedance of 200 ohm. What is value of voltage

at infinity.

(A) 8 V (B) 12 V (C) 16 V (D) 20 V

33. Consider a 100 quarter-wave long (at 1 GHz) transmission line is connected to a 5 V, 50 source

at one end and is left open circuited at the other end. The magnitude of the voltage at the open circuit

end of the line is:

(A) 10 V (B) 5 V (C) 60 V (D) 60/7 V

34. 75 transmission line is first short-terminated and the minima locations are noted. When the short is

replaced by a resistive load the minima locations are not altered and the VSWR is measured to be 3.

What is the value of reflection coefficient :

(A) –0.25 (B) 0.25 (C) -0.5 (D) 0.5

35. Which of the following wave guide has TEM mode as fundamental mode:

P. Coaxial Q. Cylindrical R: Rectangular

(A) Only P (B) Only Q (C) Only Q&R (D) All 3

36. Consider the following statements relating to the cavity resonators:

1. For over-coupling the cavity terminals are at voltage maximum in the input line at resonance.

2. For under-coupling the cavity terminals are at the voltage minimum in the input line at

resonance.

3. For over-coupling the input terminal impedance is equal to the standing wave ratio.

4. For over-coupling the input terminal impedance is equal to the reciprocal of the standing wave

ratio.


Which of the statements given above are correct?

(A) 1, 2 & 3 (B) 1, 3 & 4 (C) 1, 2 & 4 (D) 2, 3 & 4

37. For a cavity resonator with over coupling:

Q0 = unloaded Q and = standing wave ratio Qe the loaded Q is given by

(A) Qe = Q0 (B) 0

1eQ Q

(C) 0

1e

QQ

(D)

0

1eQ Q

38. A “mode filter” has the structure of thin radial wires in a circular waveguide as shown in the diagram

given below:

Which one of the following modes is filtered out by the above mode filter ?

(A) TE01 (B) TM01 (C) TE11 (D) TM11

39. For a hollow waveguide the axial current must necessarily be

(A) a combination of conduction and displacement currents

(B) Conduction current only

(C) time-varying conduction current and displacement current

(D) Displacement current only

40. Consider the following statements:

If the narrow dimension of a standard rectangular waveguide carrying the dominant mode is reduced,

then the

1. Attenuation will increase

2. Power handling capability will increases

Which of these statements are correct ?

(A) only 1 (B) only 2 (C) both 1 and 2 (D) None

41. A mast antenna consisting of a 50 meter long vertical conductor operates over a perfectly conducting

ground plane. It is base-fed at a frequency of 600-kHz. The radiation resistance of the antenna in

ohms is

(A) 22

5

(B)

2

5

(C)

24

5

(D) 20

2

42. A uniformly spaced linear array of identical radiators having uniform amplitude of excitation and

linear phase variation with non zero gradient will produce

(A) Pencil beam at broadside (B) Fan beam

(C) Scanned cosecant beam (D) Scanned pencil beam


Y

X

Y

X

Y

X

Y

X

43. Match List I with List II and select the correct answer using the code given below the lists:

List I List II

A. 0.25, 90ºd

1.

B. 0.5, 0ºd

2.

C. 0.5, 180ºd

3.

D. 1.0, 180ºd

Code:

A B C D

(A) 4 3 1 2 (B) 2 1 3 4

(C) 4 1 3 2 (D) 2 3 1 4

44. Match List I with List II and select the correct answer using the code given below the lists :

List I List II

A. Two isotropes half wavelength apart

fed in phase

B. Two isotropes quarter wavelength apart .

90º phase shift.

C. Two isotropes quarter wavelength apart .

fed in phase

Code : A B C A B C

(A) 1 3 2 (B) 2 3 1

(C) 1 2 3 (D) 2 1 3

45. Which of the followings statement is not correct about cassegrain feed system:

(A) In normal feed, feed is located at focus but in case of cassegrain system feed radiator is located

at vertex of parabolic reflector.

(B) This system uses hyperboloid reflector which has ability to place feed at convenient point

(C) This system reduces spill over and minor lobe radiation

(D) Aperture blocking problem is also reduced by use of cassegrain feed system


3

(H)

(H)1

2

46. Match List I with List II and select the correct answer using the code given below the lists:

List I List II

A. Helical antenna 1. Fan-shaped beam, high power handling

B. Pyramidal horn antenna 2. Low bandwidth, low power handling

C. Microstrip patch antenna 3. Narrow beam, high power handling

D. Sectoral horn antenna 4. Circularly polarized beam moderate power handling

Code: A B C D A B C D

(A) 4 3 2 1 (B) 2 1 4 3

(C) 4 1 2 3 (D) 2 3 4 1

47. On a slotted line terminated in a load, the minima of the standing wave pattern measured by a

square-law device are located at (on a cm scale) 9.5, 11.0, 12.5 and 14.0. At 10.95 and 11.05 the

detected level being twice the minimum level. The VSWR on the line is

(A) 10 (B) 20 (C) 30 (D) 50

48. A slotted line is used for the measurement of VSWR. The slot is cut at the centre, because

(A) The field inside the waveguide will not be perturbed

(B) To get a good impedance matching

(C) Maximum field will be induced to the penetration probe.

(D) No field will be coupled to the probe.

49. Two identical matched hybrid T-s are joined by the E-plane arms at ports 4 and 4’ to produce a 6-

port device as shown in the given figure. If 16 mW power is fed into port 1 what will be the power

output from other five ports?

Ports ' ' '2 3 1 2 3

Power

(A) 8 4 2 2 0 mW (B) 0 8 4 4 0 mw

(C) 0 8 2 2 4 mW (D) 8 2 4 2 0 mW

50. If the scattering matrix [S] of a two port network is 0.2 90º 0.9 90º

0.9 90º 0.2 90ºS

then the network is

(A) Lossless and reciprocal (B) Lossless but not reciprocal

(C) Not lossless but reciprocal (D) Neither lossless nor reciprocal

51. Consider the following statements about Scattering parameters :

1. Scattering parameters are frequency invariant

2. Scattering matrix is unitary only for lossless networks

3. Scattering parameters are directly measurable but impedance parameters are not so




Short

Short

Matched

52. The arrangement shown in the figure is that of a hybrid T. When 100 m V of power is fed into the

collinear port-I, the power reflected back in port-I will be

(A) zero

(B) 25 m W

(C) 50 m W

(D) 100 m W

53. Which of the followings is not true about Reflex klystron:

(A) In reflex klystron velocity modulation occurs in the resonator gap

(B) It is a low power microwave source and has high stability with single frequency

(C) It has efficiency in the range of 20-30%

(D) Transit time in a repeller space of a reflex klystron must be (n+3/4) to ensure that electrons are

accelerated by gap voltage on their return journey.

54. Which of the followings is not true about TWT:

(A) It is linear beam amplifier

(B) TWT is a microwave power amplifier used in transponder of satellite

(C) In TWT microwave circuit is resonant

(D) The working of TWT is based on the interaction between moving electron and axial component

of progressive Electro magnet wave.

55. TWT is preferred over klystron due to:

(A) Higher value of gain (B) Higher value of bandwidth

(C) Higher value of output (D) More efficiency

56. Which of the following is not true about Magnetron:

(A) It is high power microwave source with a cross-field structure.

(B) It is M-type Microwave tube

(C) Generally magnetrons are operated in 2 Mode of oscillations

(D) It is used in Microwave ovens

57. The two-valley model of the Ridley- Watkins Hilsum theory is best suited to explain the working of

which one of the following?

(A) Quartz crystal oscillator (B) Gunn Diode oscillator (C) Klystron oscillator (D) R-C oscillator

58. Which of the following microwave components has got the combined characteristic of dielectric,

ohmic and radiation losses?

(A) Waveguide (B) Microstrip line (C) co-axial line (D) Parallel twin line

59. Which of the following is not true about Tunnel Diode:

(A) It is heavily doped P-N Junction diode

(B) It has low power output and is generally order of mW

(C) If Tunnel diode is biased at middle of negative resistance and is coupled to cavity then it will

produce a very high stable oscillation

(D) It has low speed and has high value of noise

60. An IMPATT diode power amplifier has a negative resistance of 40 ohm and a load resistance of 80

ohm then power gain of diode is:

(A) 4 (B) 6 (C) 9 (D) 12


Engineering Service Examination -2014

SI No.

Electronics&Telecommunication Engineering

PAPER – E.M. Theory & Microwave

(Conventional)

Time allotted: 90 Minute Maximum marks: 100

INSTRUCTIONS

Candidates should attempt Question No. 1 which is compulsory and remaining FOUR from questions taking

two each from section-A and Section-B. The number of marks carried by each question is indicated at the

end of the question. Answers must be written only in English. Assume suitable data if found necessary and

indicate the same clearly. Values of the following constants may be used wherever necessary:

Electronic charge = –1.6 × 10–9

Coulomb

Free space permeability = 4 × 10–7

Henry /m.

Free space permittivity = 9110

36

Farad/m.

Velocity of light in free space = 3 × 108 m/ sec.

Boltzmann constant = 1.38 × 10–23

joule /K.

Planck constant = 6.626 × 10–34

joule-sec.

Important: Candidates are to note that all parts and sub parts of a question are to be attempted

continuously in answer book. That is all parts and sub parts of a question being attempted must be

completed before attempting the next question.

Any page left blank in answer book must be clearly struck out. Answers that follow pages left blank

may not be given credit.


–Q+Q

Short

Matchedinput

Q.1 (a) An infinite number of concentric rings carry a charge Q each alternately positive and negative.

Their radii are 1, 2, 4, 8 meters in geometric progression as shown. The potential at the centre

will be (5)

(b) A plane wave of wavelength is traveling in a direction making an angle 45º with positive x-axis

and 90º with positive y-axis. The E field of the plane wave can be represented as: (5)

(c) The hybrid T is ideal, perfectly matched on all ports. The VSWR at the input is (5)

(d) What is basic concept behind Reflex klystron as an oscillator (5)

SECTION-A

Q.2. (a) Explain Poynting’s vector and establish the relation between E&H by use of Poynting’s

vector.(10)

(b) Write and derive the boundary conditions for Electrostatic (10)

Q.3 (a) Derive the expression for characteristic impedance in case of 2 wire transmission line (10)

(b) Compare loss less line and distortion less line (5)

(c) What is loading effect in case of transmission line (5)

Q.4 (a) Show the spatial variations of electric and magnetic fields for TE10, TE20, TE01, TE02, TE11 modes

in a rectangular waveguide.(10)

(b) Distilled water at 25ºC is characterized by = 1.7 × 10-4

mho/m and =78 0 at a frequency of 3

GHz. Its loss tangent tan is: ( = 10-9

/(36 ) F/m) (5)

(c) Explain the degenerate modes in circular wave guide (5)

SECTION-B

Q.5. (a) The parameters of a two cavity klystron are as follows: Beam voltage = 1000V, Beam current =

30 mA, Frequency = 9 GHz, gap spacing in either cavity = 1mm, Spacing between centers of the

cavities = 4 cm, Effective shunt impedance = 40 . (10)

Determine

(i) electron velocity

(ii) dc electron transit time

(iii) the input voltage for maximum output voltage

(iv) voltage gain in dB


(b) Sketch radiation pattern of following antennas: (2 × 5 = 10)

(i) Loop Antenna

(ii) Yagi-Uda antenna

(iii) Horn Antenna

(iv) Omini directional antenna

(v) Dipole antenna

Q.6. (a) What magic Magic–Tee Junction does and how it can be used for measurement of

impedance (10)

(b) What is the measured frequency on a wave-guide slotted line if the distance between adjacent

minima is127 cm and the width dimension of the wave-guide is 2286 cm ? (5)

(c) Explain basic working of bolometer for measurement of power. (5)

Q.7. (a) Discuss briefly the physical structure of a READ diode. Sketch the field distribution, and the

variation of currents when an a.c. voltage is applied. (10)

(b) What is the value of negative resistance in case of IMPATT diode (10)


+q

.25m

+q

–q

.25

.25

Solution: Test-4:

1. (A) x y za a a

x y z

Neither scalar nor vector but a tensor quantity.

Gradient operator or vector differential operator or vector space function

2. (B) Gradient represents max. space rate increase of scalar in magnitude as well as phase.

v v v

v x y zx y z

x y z x y z

v v va a a . dx a dya dza

x y z

v G.d

v G d cos

dvG if =90º (phase)

d

s

DV 0

A.ds.A lim definition of divergence

dv

3. (D) Divergence theorem: s vA.ds .A dv

Applied for closed surface

s L

A ds A.d :Stoke’s theorem and is valid for open surface

4. (B) 2 2

1 1 1V E E

r r r

2 3

3 4

1 1V E Dipole

r r

1 1V E Quadarpole

r r

5. (B)

2

2

0

1 qF

4 0.5

= 2

0

q

6. (C)

r

0

E a2

r xa 6a

6

x 12

0

1 10E a

2 300 2 8.85 10

xE 60a


1A

z

y

x 1A

o

a

b

r

7. (D)

d r

y y z xa a a a & x x y za a a a

So X&Z component have non zero values .

8. (C) H.d Enclosed s

J.ds by Ampere’s Law

zds r.dr.d .a

Given , , 0 2

rJ r z J dz

a

d H 2 r

a 2

0, 2

r 0

J rJ r, z .r dr d

a

3 3

0

2

r aJ

a 3

9. (B) Magnetic field: Solenoidial field

Electric field : Conservative field

10. (C) 2V . V 0 For scalar it is divergence of gradient)

2V .V V For vector

11. (A) Any solution to Laplacian or Poisson equation which satisfies boundary condn. must have

only unique solution.

Uniqueness theorem: 1 2V & V at identical.

12. (C) J E (electric field) B H (magnetic field)

s

I J.ds

B.ds

13. (A) T C DJ J J

C DJ E J j E

TJ E j E E j ' j " E

TJ E j 'E "E

TJ E " j 'E

14. (B)

15. (B) JD = dE/dt

JD = . 0.1 t. (-e-t) + 0.1 e

-t


y

s=+90º

xy

s=+90º

x

s=–90ºz

JD/at t = 0 = 0.1. e0 . 40 = 0.4 0

So current crossing will be JD.area=0.04 0

16. (C) j t y

0E E ax jaz e

0E

Z leads to x

Right hand system

17. A. For wave propagation frequency of propagation f>fc

For dominant mode TE10

10

10

2 2 1.5 2 6

3 10( ) 5

6

c r

c

c

a cm

so f TE GHz

Here f f so it will pass through

18. (D) 2 2

s v

d H EE H ds E.J dV dV

dt 2 2

L.H.S term : Power flowing out of region or outward instantaneous flow

R.H.S term-1: Instantaneous power generated due to heat effect

R.H.S term-2: Rate of decrease of stored electromagnetic energy

19. (A) 1

2

ve

v

ee 50 ln50 log 50 Nseper

Attenuation in edB 8.686 log 50dB

20. (B)

dHE

dt

dH

Edt

dEH

dt

222 2 2

2

2 2

d E.E E j E E k E

dt

.E E k E 0

21. (C) 2

2

2

d EE E

dt

if j t

0E E e


2 2 2 2

2 2

E E 0 & k

E k E 0

22 2

Put jkx xx 02 2

E E. E E e

z t

wave is propagating in +z direction

22. (B) 0i

0

1tan

81 9

i 6.34º

90º 6.34º 83.66º

23. (B)

For perfect conductor :

n

tan

c

1 tan & 90º

For perfect conductor n2

24. (D) *

avg

1P Re E H

2

*

comp

1P E H

2

instP E H

25. (B) General equation

x y zj t .x .y .z

0E E e

2 2 2

x cosA cos A cos B cos C 1

2

2 2

y

1cos B 0 cos C 1

2

2

z

1 3cosC cos C 1

4 4

3

cosC2

C 30º

x

2 1

2

y

20 0

z

2 3 3

2


12 12+–

+–100V 10V

+–24V +

–24V

+– 5V z0

+

–

voc

3 3j t x 0 z

0E E e

26. (D) E 0 .B 0

27. (A) Magnetic current is consist of displacement current&no displacement current

28. (C) Energy stored in form of EM field.

Through the wine.

29. (D) 6 6

6 6 12

0

10 10tan

2 10 10 5 2 10 5 8.85 10

32 10

1 lossless 0 Perfect dielectric

30. (D)

50 5025

100

50 || 50 25

iZ 50 (Transmission line)

31. (C) 0

r

60z ln b / a a 10mm

0z 60

60 b

60 ln101

b

e b 27.2mm10

32. (C)

Transient analysis in Transmission line : 24

V( ) 200 16V300

33. (A)

4

line behaves as step up on step down transform

0 0 0

s s s

v z v 100

v z v 50 oV 2 5 10volt ;

34. (C) Location of 1st minima decides phase

jminX 1720º k k e

4


Short circuited minima no position change

ve

3 1 2 1K F .5

3 1 4 2

35. (A) If inner conductor is present then only TEM mode can appear.

36. (A)

37. (C)

L 0 ext

1 1 1

Q Q Q

0ext

QQ

k

(i) Critical coupling k = 1

0L

QQ

2

(ii) Under coupling k < 1

Minima at cavity

in

1z

VSWR

0

L

L 0

k 1 P Q1& Q

Q Q P 1

VSWR

(iii) Over coupling k > 1

Maxima at cavity

inz VSWR

0L

QQ

1

38. (B) TM01 :–

TE01 :– TE11 :

TM11 :–

39. (D) Axial current displacement current


d /2l dh

centrefeeding

l2

=h

Base feeding

40. (A) 1

Attenuationb

4 2

handling maxP 6.64 10 E ab

41. (A)

Case (i) dl

2

2 dRr 80

Case (ii)

2280 dRr

2

2

2 d40

2

2 dhRr 160

Practical antenna:

2

2 e80

2

22 2 heRr 40 le / 160

Vertical grounded antenna

22Rr 160 he /

22

22

Rr 80 le /

e / 2

Rr 20 /

22Rr 10 /

22Rr 40 h /

2

2 50Rr 40

500

22

Rr5


d1 d2

vmin

42. (C)

if = 0 Broadside array: Fan Beam

if 90º Pencil Beam

if 0 Scanned cosecant beam

43. (D) d 0 dcos2

2

cos 02

T

0

EA.F 2cos

E 2

cos

cos

A.F 2cos2

44. (B)

45. (D)

46. (A) Sectoral horn : Fan beam

Pyramidal horn : Pencil beam

47. (A)

g

2 1

VSWRd d

g 3

g

1.52

1 2d 10.95; d 11.05

3 3

VSWR11.05 1095 0.1

VSWR 10

48. (A)

Cut at center

So that field inside the W.G

will not be perturbed


50mw

25mw0

25mw

50mw

5mw

25mw100mw

25mw25+25mw

50mw

matches

beach

E 4

H

3

1

2Auxiliary arm

Co-linear arm

4

288

161

4

0

3(H)

49. (B)

50. (C)

T

*

For Reciprocal s s

s s I valid only for loss less

51. (B) Frequency variant s-parameters varies

52. (C)

53. (D) It is decelerated

54. (C) TWT BW, Non-Resonant

55. (B)

56. (C)

57. (B)

58. (B)

59. (D)

60. (C)

2

T L

T L

R RP

R R

test booklet series test booklet e.m. theory & … · 2. encode clearly the test booklet series...

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